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                                                                                                                             January 4, 2006

                                                                                                                             Part II

                                                                                                                             Protection Agency
                                                                                                                             40 CFR Parts 9, 141, and 142
                                                                                                                             National Primary Drinking Water
                                                                                                                             Regulations: Stage 2 Disinfectants and
                                                                                                                             Disinfection Byproducts Rule; Final Rule
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                                       388                     Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                       ENVIRONMENTAL PROTECTION                                                   reducing peak and average levels of                      Publicly available docket materials
                                       AGENCY                                                                     DBPs in drinking water supplies.                      are available either electronically
                                                                                                                     The Stage 2 DBPR applies to public                 through http://www.regulations.gov or
                                       40 CFR Parts 9, 141, and 142                                               water systems (PWSs) that are                         in hard copy at the Water Docket, EPA/
                                                                                                                  community water systems (CWSs) or                     DC, EPA West, Room B102, 1301
                                       [EPA–HQ–OW–2002–0043; FRL–8012–1]
                                                                                                                  nontransient noncommunity water                       Constitution Ave., NW., Washington,
                                       RIN 2040–AD38                                                              systems (NTNCWs) that add a primary                   DC. The Public Reading Room is open
                                                                                                                  or residual disinfectant other than                   from 10 a.m. to 4 p.m., Monday through
                                       National Primary Drinking Water                                            ultraviolet light or deliver water that has           Friday, excluding legal holidays. The
                                       Regulations: Stage 2 Disinfectants and                                     been treated with a primary or residual               telephone number for the Public
                                       Disinfection Byproducts Rule                                               disinfectant other than ultraviolet light.            Reading Room is (202) 566–1744, and
                                       AGENCY:  Environmental Protection                                             This rule also makes minor                         the telephone number for the Water
                                       Agency (EPA).                                                              corrections to drinking water                         Docket is (202) 566–2426.
                                                                                                                  regulations, specifically the Public
                                       ACTION: Final rule.                                                                                                              FOR FURTHER INFORMATION CONTACT:     For
                                                                                                                  Notification tables. New endnotes were
                                       SUMMARY: The Environmental Protection                                      added to these tables in recent                       technical inquiries, contact Tom
                                       Agency (EPA) is promulgating today’s                                       rulemakings; however, the                             Grubbs, Standards and Risk
                                       final rule, the Stage 2 Disinfectants and                                  corresponding footnote numbering in                   Management Division, Office of Ground
                                       Disinfection Byproducts Rule (DBPR), to                                    the tables was not changed. In addition,              Water and Drinking Water (MC 4607M),
                                       provide for increased protection against                                   this rule makes a minor correction to the             Environmental Protection Agency, 1200
                                       the potential risks for cancer and                                         Stage 1 Disinfectants and Disinfection                Pennsylvania Ave., NW., Washington,
                                       reproductive and developmental health                                      Byproducts Rule by replacing a sentence               DC 20460; telephone number: (202)
                                       effects associated with disinfection                                       that was inadvertently removed.                       564–5262; fax number: (202) 564–3767;
                                       byproducts (DBPs). The final Stage 2                                       DATES: This final rule is effective on                e-mail address: grubbs.thomas@epa.gov.
                                       DBPR contains maximum contaminant                                          March 6, 2006. For judicial review                    For general information, contact the
                                       level goals for chloroform,                                                purposes, this final rule is promulgated              Safe Drinking Water Hotline, Telephone
                                       monochloroacetic acid and                                                  as January 4, 2006. The incorporation by              (800) 426–4791. The Safe Drinking
                                       trichloroacetic acid; National Primary                                     reference of certain publications listed              Water Hotline is open Monday through
                                       Drinking Water Regulations, which                                          in the rule is approved by the Director               Friday, excluding legal holidays, from
                                       consist of maximum contaminant levels                                      of the Federal Register as of March 6,                10 a.m. to 4 p.m. Eastern Time.
                                       (MCLs) and monitoring, reporting, and                                      2006.                                                 SUPPLEMENTARY INFORMATION:
                                       public notification requirements for                                       ADDRESSES: EPA has established a
                                       total trihalomethanes (TTHM) and                                           docket for this action under Docket ID                I. General Information
                                       haloacetic acids (HAA5); and revisions                                     No. EPA–HQ–OW–2002–0043. All                          A. Does This Action Apply to Me?
                                       to the reduced monitoring requirements                                     documents in the docket are listed on
                                       for bromate. This document also                                            the http://www.regulations.gov Web                      Entities potentially regulated by the
                                       specifies the best available technologies                                  site.                                                 Stage 2 DBPR are community and
                                       for the final MCLs. EPA is also                                               Although listed in the index, some                 nontransient noncommunity water
                                       approving additional analytical methods                                    information is not publicly available,                systems that add a primary or residual
                                       for the determination of disinfectants                                     e.g., CBI or other information whose                  disinfectant other than ultraviolet light
                                       and DBPs in drinking water. EPA                                            disclosure is restricted by statute.                  or deliver water that has been treated
                                       believes the Stage 2 DBPR will reduce                                      Certain other material, such as                       with a primary or residual disinfectant
                                       the potential risks of cancer and                                          copyrighted material, is not placed on                other than ultraviolet light. Regulated
                                       reproductive and developmental health                                      the Internet and will be publicly                     categories and entities are identified in
                                       effects associated with DBPs by                                            available only in hard copy form.                     the following chart.

                                                                    Category                                                                             Examples of regulated entities

                                       Industry ...............................................................    Community and nontransient noncommunity water systems that use a primary or residual dis-
                                                                                                                    infectant other than ultraviolet light or deliver water that has been treated with a primary or
                                                                                                                    residual disinfectant other than ultraviolet light.
                                       State, Local, Tribal, or Federal Governments ....                           Community and nontransient noncommunity water systems that use a primary or residual dis-
                                                                                                                    infectant other than ultraviolet light or deliver water that has been treated with a primary or
                                                                                                                    residual disinfectant other than ultraviolet light.

                                          This table is not intended to be                                        the section entitled ‘‘coverage’’ (§ 141.3)           B. How Can I Get Copies of This
                                       exhaustive, but rather provides a guide                                    in Title 40 of the Code of Federal                    Document and Other Related
                                       for readers regarding entities likely to be                                Regulations and applicability criteria in             Information?
                                       regulated by this action. This table lists                                 § 141.600 and 141.620 of today’s                         See the ADDRESSES section for
                                       the types of entities that EPA is now                                      proposal. If you have questions                       information on how to receive a copy of
                                       aware could potentially be regulated by                                    regarding the applicability of this action            this document and related information.
                                       this action. Other types of entities not                                   to a particular entity, contact the person
                                                                                                                                                                        Regional contacts:
                                       listed in the table could also be                                          listed in the preceding FOR FURTHER
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                                                                                                                                                                        I. Kevin Reilly, Water Supply Section,
                                       regulated. To determine whether your                                       INFORMATION CONTACT section.
                                                                                                                                                                             JFK Federal Bldg., Room 203,
                                       facility is regulated by this action, you                                                                                             Boston, MA 02203, (617) 565–3616.
                                       should carefully examine the definition
                                                                                                                                                                        II. Michael Lowy, Water Supply Section,
                                       of ‘‘public water system’’ in § 141.2 and                                                                                             290 Broadway, 24th Floor, New

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                              389

                                             York, NY 10007–1866, (212) 637–                     acid, trichloroacetic acid,                          SBAR Small Business Advisory
                                             3830.                                               monobromoacetic acid, and                              Review
                                       III. Jason Gambatese, Drinking Water                      dibromoacetic acid)                                  SBREFA Small Business Regulatory
                                             Section (3WM41), 1650 Arch Street,                HAN Haloacetonitriles                                    Enforcement Fairness Act
                                             Philadelphia, PA 19103–2029, (215)                  (trichloroacetonitrile,                              SDWA Safe Drinking Water Act, or the
                                             814–5759.                                           dichloroacetonitrile,                                  ‘‘Act,’’ as amended in 1996
                                       IV. Robert Burns, Drinking Water                          bromochloroacetonitrile, and                         SER Small Entity Representative
                                             Section, 61 Forsyth Street SW.,                     dibromoacetonitrile)                                 SGA Small for gestational age
                                             Atlanta, GA 30303, (404) 562–9456.                IC Ion chromatograph                                   SUVA Specific ultraviolet absorbance
                                       V. Miguel Del Toral, Water Supply                       IC/ICP–MS Ion chromatograph                            SWAT Surface Water Analytical Tool
                                             Section, 77 W. Jackson Blvd.,                       coupled to an inductively coupled                    SWTR Surface Water Treatment Rule
                                             Chicago, IL 60604, (312) 886–5253.                  plasma mass spectrometer                             TC Total coliforms
                                       VI. Blake L. Atkins, Drinking Water                     IDSE Initial distribution system                       TCAA Trichloroacetic acid
                                             Section, 1445 Ross Avenue, Dallas,                  evaluation                                           TCR Total Coliform Rule
                                             TX 75202, (214) 665–2297.                         ILSI International Life Sciences                       THM Trihalomethane
                                       VII. Douglas J. Brune, Drinking Water                     Institute                                            TOC Total organic carbon
                                             Management Branch, 901 North 5th                  IESWTR Interim Enhanced Surface                        TTHM Total trihalomethanes (sum of
                                             Street, Kansas City, KS 66101, (800)                Water Treatment Rule                                   four THMs: chloroform,
                                             233–0425.                                         IPCS International Programme on                          bromodichloromethane,
                                       VIII. Bob Clement, Public Water Supply                    Chemical Safety                                        dibromochloromethane, and
                                             Section (8P2-W-MS), 999 18th                      IRIS Integrated Risk Information                         bromoform)
                                             Street, Suite 500, Denver, CO                       System (EPA)                                         TWG Technical work group
                                             80202–2466, (303) 312–6653.                       LOAEL Lowest observed adverse effect                   UMRA Unfunded Mandates Reform
                                       IX. Bruce Macler, Water Supply Section,                   level                                                  Act
                                             75 Hawthorne Street, San                          LRAA Locational running annual                         UV 254 Ultraviolet absorption at 254
                                             Francisco, CA 94105, (415) 972–                     average                                                nm
                                             3569.                                             LT1ESTWR Long Term 1 Enhanced                          VSL Value of Statistical Life
                                       X. Wendy Marshall, Drinking Water                         Surface Water Treatment Rule                         WTP Willingness To Pay
                                             Unit, 1200 Sixth Avenue (OW–136),                 LT2ESTWR Long Term 2 Enhanced                          Table of Contents
                                             Seattle, WA 98101, (206) 553–1890.                  Surface Water Treatment Rule
                                                                                               MBAA Monobromoacetic acid                              I. General Information
                                       Abbreviations Used in This Document                     MCAA Monochloroacetic acid                                A. Does This Action Apply to Me?
                                                                                                                                                         B. How Can I Get Copies of This Document
                                       ASDWA Association of State Drinking                     MCL Maximum contaminant level                                and Other Related Information?
                                         Water Administrators                                  MCLG Maximum contaminant level                         II. Summary of the Final Rule
                                       ASTM American Society for Testing                         goal                                                    A. Why is EPA Promulgating the Stage 2
                                         and Materials                                         M–DBP Microbial and disinfection                             DBPR?
                                       AWWA American Water Works                                 byproducts mg/L Milligram per liter                     B. What Does the Stage 2 DBPR Require?
                                         Association                                           MRL Minimum reporting level                               1. Initial Distribution System Evaluation
                                       AwwaRF American Water Works                             MRDL Maximum residual disinfectant                        2. Compliance and monitoring
                                         Association Research Foundation                         level                                                      requirements
                                       BAT Best available technology                           MRDLG Maximum residual                                    3. Operational Evaluation Levels
                                       BCAA Bromochloroacetic acid                                                                                       4. Consecutive systems
                                                                                                 disinfectant level goal
                                                                                                                                                         C. Correction of § 141.132
                                       BDCM Bromodichloromethane                               NDMA N-nitrosodimethylamine                            III. Background
                                       CDBG Community Development Block                        NDWAC National Drinking Water                             A. Statutory Requirements and Legal
                                         Grant                                                   Advisory Council                                           Authority
                                       CWS Community water system                              NF Nanofiltration                                         B. What is the Regulatory History of the
                                       DBAA Dibromoacetic acid                                 NOAEL No Observed Adverse Effect                             Stage 2 DBPR and How Were
                                       DBCM Dibromochloromethane                                 Level                                                      Stakeholders Involved?
                                       DBP Disinfection byproduct                              NODA Notice of data availability                          1. Total Trihalomethanes Rule
                                       DBPR Disinfectants and Disinfection                     NPDWR National primary drinking                           2. Stage 1 Disinfectants and Disinfection
                                         Byproducts Rule                                         water regulation                                           Byproducts Rule
                                       DCAA Dichloroacetic acid                                NRWA National Rural Water                                 3. Stakeholder involvement
                                                                                                                                                         a. Federal Advisory Committee process
                                       EA Economic analysis                                      Association                                             b. Other outreach processes
                                       EC Enhanced coagulation                                 NTNCWS Nontransient                                       C. Public Health Concerns to be Addressed
                                       EDA Ethylenediamine                                       noncommunity water system                               1. What are DBPs?
                                       EPA United States Environmental                         NTP National Toxicology Program                           2. DBP Health Effects
                                         Protection Agency                                     NTTAA National Technology Transfer                        a. Cancer health effects
                                       ESWTR Enhanced Surface Water                              and Advancement Act                                     i. Epidemiology
                                         Treatment Rule                                        OMB Office of Management and                              ii. Toxicology
                                       FACA Federal Advisory Committee                           Budget                                                  b. Reproductive and developmental health
                                         Act                                                   PAR Population attributable risk                             effects
                                       GAC Granular activated carbon                           PE Performance evaluation                                 i. Epidemiology
                                       GC/ECD Gas chromatography using                                                                                   ii. Toxicology
                                                                                               PWS Public water system
                                                                                                                                                         c. Conclusions
                                         electron capture detection                            RAA Running annual average                                D. DBP Occurrence and DBP Control
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                                       GWR Ground Water Rule                                   RFA Regulatory Flexibility Act                            1. Occurrence
                                       GWUDI Ground water under the direct                     RfD Reference dose                                        2. Treatment
                                         influence of surface water                            RSC Relative source contribution                          E. Conclusions for Regulatory Action
                                       HAA5 Haloacetic acids (five) (sum of                    RUS Rural Utility Service                              IV. Explanation of Today’s Action
                                         monochloroacetic acid, dichloroacetic                 SAB Science Advisory Board                                A. MCLGs

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                                       390               Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                          1. Chloroform MCLG                                     M. System Reporting and Recordkeeping                  B. Paperwork Reduction Act
                                          a. Today’s rule                                           Requirements                                        C. Regulatory Flexibility Act
                                          b. Background and analysis                             1. Today’s rule                                        D. Unfunded Mandates Reform Act
                                          c. Summary of major comments                           2. Summary of major comments                           E. Executive Order 13132: Federalism
                                          2. HAA MCLGs: TCAA and MCAA                            N. Approval of Additional Analytical                   F. Executive Order 13175: Consultation
                                          a. Today’s rule                                           Methods                                                and Coordination With Indian Tribal
                                          b. Background and analysis                             1. Today’s Rule                                           Governments
                                          c. Summary of major comments                           2. Background and Analysis                             G. Executive Order 13045: Protection of
                                          B. Consecutive Systems                                 O. Laboratory Certification and Approval                  Children from Environmental Health
                                          1. Today’s Rule                                        1. PE acceptance criteria                                 Risks and Safety Risks
                                          2. Background and analysis                             a. Today’s rule                                        H. Executive Order 13211: Actions
                                          3. Summary of major comments                           b. Background and analysis                                Concerning Regulations That
                                          C. LRAA MCLs for TTHM and HAA5                         c. Summary of major comments                              Significantly Affect Energy Supply,
                                          1. Today’s rule                                        2. Minimum reporting limits                               Distribution, or Use
                                          2. Background and analysis                             a. Today’s rule                                        I. National Technology Transfer and
                                          3. Summary of major comments                           b. Background and analysis                                Advancement Act
                                          D. BAT for TTHM and HAA5                               c. Summary of major comments                           J. Executive Order 12898: Federal Actions
                                          1. Today’s rule                                        P. Other regulatory changes                               to Address Environmental Justice in
                                          2. Background and analysis                           V. State Implementation                                     Minority Populations or Low-Income
                                          3. Summary of major comments                           A. Today’s rule                                           Populations
                                          E. Compliance Schedules                                1. State Primacy Requirements for                      K. Consultations with the Science
                                          1. Today’s rule                                           Implementation Flexibility
                                                                                                                                                           Advisory Board, National Drinking
                                          2. Background and analysis                             2. State recordkeeping requirements
                                                                                                                                                           Water Advisory Council, and the
                                          3. Summary of major comments                           3. State reporting requirements
                                                                                                                                                           Secretary of Health and Human Services
                                          F. Initial Distribution System Evaluation              4. Interim primacy
                                                                                                                                                        L. Plain Language
                                             (IDSE)                                              5. IDSE implementation
                                                                                                 B. Background and Analysis                             M. Analysis of the Likely Effect of
                                          1. Today’s rule                                                                                                  Compliance With the Stage 2 DBPR on
                                          a. Applicability                                       C. Summary of Major Comments
                                                                                               VI. Economic Analysis                                       the Technical, Managerial, and Financial
                                          b. Data collection                                                                                               Capacity of Public Water Systems
                                          i. Standard monitoring                                 A. Regulatory Alternatives Considered
                                                                                                 B. Analyses that Support Today’s Final                 N. Congressional Review Act
                                          ii. System specific study                                                                                   VIII. References
                                          iii. 40/30 certification
                                                                                                 1. Predicting water quality and treatment            II. Summary of the Final Rule
                                          c. Implementation
                                          2. Background and analysis
                                                                                                 2. Estimating benefits                               A. Why is EPA Promulgating the Stage
                                          a. Standard monitoring
                                                                                                 3. Estimating costs                                  2 DBPR?
                                          b. Very small system waivers
                                                                                                 4. Comparing regulatory alternatives
                                          c. 40/30 certifications                                C. Benefits of the Stage 2 DBPR                         The Environmental Protection Agency
                                          d. System specific studies                             1. Nonquantified benefits                            is finalizing the Stage 2 Disinfectants
                                          e. Distribution System Schematics                      2. Quantified benefits                               and Disinfection Byproduct Rule
                                          3. Summary of major comments                           3. Timing of benefits accrual                        (DBPR) to reduce potential cancer risks
                                          G. Monitoring Requirements and                         D. Costs of the Stage 2 DBPR
                                             Compliance Determination for TTHM                                                                        and address concerns with potential
                                                                                                 1. Total annualized present value costs              reproductive and developmental risks
                                             and HAA5 MCLs                                       2. PWS costs
                                          1. Today’s Rule                                                                                             from DBPs. The Agency is committed to
                                                                                                 a. IDSE costs
                                          a. IDSE Monitoring                                     b. PWS treatment costs                               ensuring that all public water systems
                                          b. Routine Stage 2 Compliance Monitoring               c. Monitoring costs                                  provide clean and safe drinking water.
                                          i. Reduced monitoring                                  3. State/Primacy agency costs                        Disinfectants are an essential element of
                                          ii. Compliance determination                           4. Non-quantified costs                              drinking water treatment because of the
                                          2. Background and Analysis                             E. Household Costs of the Stage 2 DBPR               barrier they provide against harmful
                                          3. Summary of Major Comments                           F. Incremental Costs and Benefits of the             waterborne microbial pathogens.
                                          H. Operational Evaluation Requirements                    Stage 2 DBPR
                                             initiated by TTHM and HAA5 Levels                                                                        However, disinfectants react with
                                                                                                 G. Benefits From the Reduction of Co-
                                          1. Today’s rule                                                                                             naturally occurring organic and
                                                                                                    occurring Contaminants
                                          2. Background and analysis                             H. Potential Risks From Other                        inorganic matter in source water and
                                          3. Summary of major comments                              Contaminants                                      distribution systems to form
                                          I. MCL, BAT, and Monitoring for Bromate                1. Emerging DBPs                                     disinfection byproducts (DBPs) that may
                                          1. Today’s rule                                        2. N-nitrosamines                                    pose health risks. The Stage 2 DBPR is
                                          2. Background and analysis                             3. Other DBPs                                        designed to reduce the level of exposure
                                          a. Bromate MCL                                         I. Effects of the Contaminant on the                 from DBPs without undermining the
                                          b. Criterion for reduced bromate                          General Population and Groups within              control of microbial pathogens. The
                                             monitoring                                             the General Population that are
                                          3. Summary of major comments                                                                                Long Term 2 Enhanced Surface Water
                                                                                                    Identified as Likely To Be at Greater Risk
                                          J. Public Notice Requirements                             of Adverse Health Effects                         Treatment Rule (LT2ESWTR) is being
                                          1. Today’s rule                                        J. Uncertainties in the Risk, Benefit, and           finalized and implemented
                                          2. Background and analysis                                Cost Estimates for the Stage 2 DBPR               simultaneously with the Stage 2 DBPR
                                          3. Summary of major comments                           K. Benefit/Cost Determination for the Stage          to ensure that drinking water is
                                          K. Variances and Exemptions                               2 DBPR                                            microbiologically safe at the limits set
                                          1. Today’s Rule                                        L. Summary of Major Comments                         for DBPs.
                                          2. Background and Analysis                             1. Interpretation of health effects studies             Congress required EPA to promulgate
                                          a. Variances                                           2. Derivation of benefits                            the Stage 2 DBPR as part of the 1996
                                          b. Affordable Treatment Technologies for               3. Use of SWAT
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                                             Small Systems                                       5. Unanticipated risk issues
                                                                                                                                                      Safe Drinking Water Act (SDWA)
                                          c. Exemptions                                          6. Valuation of cancer cases avoided                 Amendments (section 1412(b)(2)(C)).
                                          3. Summary of major comments                         VII. Statutory and Executive Order Reviews             The Stage 2 DBPR augments the Stage
                                          L. Requirements for Systems to Use                     A. Executive Order 12866: Regulatory                 1 DBPR that was finalized in 1998 (63
                                             Qualified Operators                                    Planning and Review                               FR 69390, December 16, 1998) (USEPA

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                           391

                                       1998a). The goal of the Stage 2 DBPR is                 reductions of DBPs in distribution                        The IDSE is designed to offer
                                       to target the highest risk systems for                  systems.                                               flexibility to public water systems. The
                                       changes beyond those required for Stage                    The Stage 2 DBPR presents a risk-                   IDSE requires TTHM and HAA5
                                       1 DBPR. Today’s rule reflects consensus                 targeting approach to reduce risks from                monitoring for one year on a regular
                                       recommendations from the Stage 2                        DBPs. The new requirements provide                     schedule that is determined by source
                                       Microbial/Disinfection Byproducts (M–                   for more consistent, equitable protection              water type and system size.
                                       DBP) Federal Advisory Committee (the                    from DBPs across the entire distribution               Alternatively, systems have the option
                                       Advisory Committee) as well as public                   system and the reduction of DBP peaks.                 of performing a site-specific study based
                                       comments.                                               New risk-targeting provisions require                  on historical data, water distribution
                                         New information on health effects,                    systems to first identify their risk level;            system models, or other data; and
                                       occurrence, and treatment has become                    then, only those systems with the                      waivers are available under certain
                                       available since the Stage 1 DBPR that                   greatest risk will need to make                        circumstances. The IDSE requirements
                                       supports the need for the Stage 2 DBPR.                 operational or treatment changes. The                  are discussed in Sections IV.E, IV.F.,
                                       EPA has completed a more extensive                      Stage 2 DBPR, in conjunction with the                  and IV.G of this preamble and in
                                       analysis of health effects, particularly                LT2ESWTR, will help public water                       subpart U of the rule language.
                                       reproductive and developmental                          systems deliver safer water to
                                       endpoints, associated with DBPs since                   Americans with the benefits of                         2. Compliance and Monitoring
                                       the Stage 1 DBPR. Some recent studies                   disinfection to control pathogens and                  Requirements
                                       on both human epidemiology and                          with fewer risks from DBPs.                               As in Stage 1, the Stage 2 DBPR
                                       animal toxicology have shown possible                                                                          focuses on monitoring for and reducing
                                                                                               B. What Does the Stage 2 DBPR Require?                 concentrations of two classes of DBPs:
                                       associations between chlorinated
                                       drinking water and reproductive and                        The risk-targeting components of the                total trihalomethanes (TTHM) and
                                       developmental endpoints such as                         Stage 2 DBPR focus the greatest amount                 haloacetic acids (HAA5). These two
                                       spontaneous abortion, stillbirth, neural                of change where the greatest amount of                 groups of DBPs act as indicators for the
                                       tube and other birth defects, intrauterine              risk may exist. Therefore, the provisions              various byproducts that are present in
                                       growth retardation, and low birth                       of the Stage 2 DBPR focus first on                     water disinfected with chlorine or
                                       weight. While results of these studies                  identifying the higher risks through the               chloramine. This means that
                                       have been mixed, EPA believes they                      Initial Distribution System Evaluation                 concentrations of TTHM and HAA5 are
                                       support a potential hazard concern.                     (IDSE). The rule then addresses                        monitored for compliance, but their
                                       New epidemiology and toxicology                         reducing exposure and lowering DBP                     presence in drinking water is
                                       studies evaluating bladder, colon, and                  peaks in distribution systems by using                 representative of many other
                                       rectal cancers have increased the weight                a new method to determine MCL                          chlorination DBPs that may also occur
                                       of evidence linking these health effects                compliance (locational running annual                  in the water; thus, a reduction in TTHM
                                       to DBP exposure. The large number of                    average (LRAA)), defining operational                  and HAA5 generally indicates an overall
                                       people (more than 260 million                           evaluation levels, and regulating                      reduction of DBPs.
                                       Americans) exposed to DBPs and the                      consecutive systems. This section                         The second provision of the Stage 2
                                       potential cancer, reproductive, and                     briefly describes the requirements of                  DBPR is designed to address spatial
                                       developmental risks have played a                       this final rule. More detailed                         variations in DBP exposure through a
                                       significant role in EPA’s decision to                   information on the regulatory                          new compliance calculation (referred to
                                       move forward with regulatory changes                    requirements for this rule can be found                as locational running annual average)
                                       that target lowering DBP exposures                      in Section IV.                                         for TTHM and HAA5 MCLs. The MCL
                                       beyond the requirements of the Stage 1                                                                         values remain the same as in the Stage
                                                                                               1. Initial Distribution System Evaluation
                                       DBPR.                                                                                                          1. The Stage 1 DBPR running annual
                                         While the Stage 1 DBPR is predicted                      The first provision, designed to                    average (RAA) calculation allowed some
                                       to provide a major reduction in DBP                     identify higher risk systems, is the                   locations within a distribution system to
                                       exposure, national survey data suggest                  Initial Distribution System Evaluation                 have higher DBP annual averages than
                                       that some customers may receive                         (IDSE). The purpose of the IDSE is to                  others as long as the system-wide
                                       drinking water with elevated, or peak,                  identify Stage 2 DBPR compliance                       average was below the MCL. The Stage
                                       DBP concentrations even when their                      monitoring sites that represent each                   2 DBPR bases compliance on a
                                       distribution system is in compliance                    system’s highest levels of DBPs. Because               locational running annual average
                                       with the Stage 1 DBPR. Some of these                    Stage 2 DBPR compliance will be                        (LRAA) calculation, where the annual
                                       peak concentrations are substantially                   determined at these new monitoring                     average at each sampling location in the
                                       greater than the Stage 1 DBPR maximum                   sites, only those systems that identify                distribution system will be used to
                                       contaminant levels (MCLs) and some                      elevated concentrations of TTHM and                    determine compliance with the MCLs of
                                       customers receive these elevated levels                 HAA5 will need to make treatment or                    0.080 mg/L and 0.060 mg/L for TTHM
                                       of DBPs on a consistent basis. The new                  process changes to bring the system into               and HAA5, respectively. The LRAA will
                                       survey results also show that Stage 1                   compliance with the Stage 2 DBPR. By                   reduce exposures to high DBP
                                       DBPR monitoring sites may not be                        identifying compliance monitoring sites                concentrations by ensuring that each
                                       representative of higher DBP                            with the highest concentrations of                     monitoring site is in compliance with
                                       concentrations that occur in distribution               TTHM and HAA5 in each system’s                         the MCLs as an annual average, while
                                       systems. In addition, new studies                       distribution system, the IDSE will offer               providing all customers drinking water
                                       indicate that cost-effective technologies               increased assurance that MCLs are being                that more consistently meets the MCLs.
                                       including ultraviolet light (UV) and                    met across the distribution system and                 A more detailed discussion of Stage 2
                                       granular activated carbon (GAC) may be                  that customers are receiving more                      DBPR MCL requirements can be found
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                                       very effective at lowering DBP levels.                  equitable public health protection. Both               in Sections IV.C, IV.E, and IV.G of this
                                       EPA’s analysis of this new occurrence                   treatment changes and awareness of                     preamble and in § 141.64(b)(2) and (3)
                                       and treatment information indicates that                TTHM and HAA5 levels resulting from                    and subpart V of the rule language.
                                       significant public health benefits may be               the IDSE will allow systems to better                     The number of compliance
                                       achieved through further, cost-effective                control for distribution system peaks.                 monitoring sites is based on the

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                                       population served and the source water                  the Stage 1 Disinfection Byproducts                    on the health of persons,’’ is ‘‘known to
                                       type. EPA believes that population-                     Rule. This rule corrects a technical error             occur or there is a substantial likelihood
                                       based monitoring provides better risk-                  made in the January 16, 2001, Federal                  that the contaminant will occur in
                                       targeting and is easier to implement.                   Register Notice (66 FR 3769) (see page                 public water systems with a frequency
                                       Section IV.G describes population-based                 3770). This rule restores the following                and at levels of public health concern,’’
                                       monitoring and how it affects systems                   sentence that was inadvertently                        and for which ‘‘in the sole judgement of
                                       complying with this rule.                               removed from § 141.132 (b)(1)(iii),                    the Administrator, regulation of such
                                          The Stage 2 DBPR includes new                        ‘‘Systems on a reduced monitoring                      contaminant presents a meaningful
                                       MCLGs for chloroform,                                   schedule may remain on that reduced                    opportunity for health risk reduction for
                                       monochloroacetic acid, and                              schedule as long as the average of all                 persons served by public water
                                       trichloroacetic acid, but these new                     samples taken in the year (for systems                 systems’’ (SDWA section 1412(b)(1)(A)).
                                       MCLGs do not affect the MCLs for                        which must monitor quarterly) or the                   MCLGs are non-enforceable health goals
                                       TTHM or HAA5.                                           result of the sample (for systems which                set at a level at which ‘‘no known or
                                       3. Operational Evaluation Levels                        must monitor no more frequently than                   anticipated adverse effects on the health
                                                                                               annually) is no more than 0.060 mg/L                   of persons occur and which allows an
                                          The IDSE and LRAA calculation will                   and 0.045 mg/L for TTHMs and HAA5,                     adequate margin of safety.’’ These
                                       lead to lower DBP concentrations                        respectively.’’ This text had been part of             health goals are published at the same
                                       overall and reduce short term exposures                 the original regulation when it was                    time as the NPDWR (SDWA sections
                                       to high DBP concentrations in certain                   codified in the CFR on December 16,                    1412(b)(4) and 1412(a)(3)).
                                       areas, but this strengthened approach to                1998. However, as a result of a                           SDWA also requires each NPDWR for
                                       regulating DBPs will still allow                        subsequent amendment to that                           which an MCLG is established to
                                       individual DBP samples above the MCL                    regulatory text, the text discussed today              specify an MCL that is as close to the
                                       even when systems are in compliance                     was removed. EPA recognized the error                  MCLG as is feasible (sections 1412(b)(4)
                                       with the Stage 2 DBPR. Today’s rule                     only after publication of the new                      and 1401(1)(C)). The Agency may also
                                       requires systems that exceed operational                amendment, and is now correcting the                   consider additional health risks from
                                       evaluation levels (referred to as                       error. EPA is merely restoring to the                  other contaminants and establish an
                                       significant excursions in the proposed                  CFR language that EPA had                              MCL ‘‘at a level other than the feasible
                                       rule) to evaluate system operational                    promulgated on December 16, 1998.                      level, if the technology, treatment
                                       practices and identify opportunities to                 EPA is not creating any new rights or                  techniques, and other means used to
                                       reduce DBP concentrations in the                        obligations by this technical correction.              determine the feasible level would
                                       distribution system. This provision will                Thus, additional notice and public                     result in an increase in the health risk
                                       curtail peaks by providing systems with                 comment is not necessary. EPA finds                    from drinking water by—(i) increasing
                                       a proactive approach to remain in                       that this constitutes ‘‘good cause’’ under             the concentration of other contaminants
                                       compliance. Operational evaluation                      5 U.S.C. 553(b)(B).                                    in drinking water; or (ii) interfering with
                                       requirements are discussed in greater                                                                          the efficacy of drinking water treatment
                                                                                               III. Background                                        techniques or processes that are used to
                                       detail in Section IV.H.
                                                                                                  A combination of factors influenced                 comply with other national primary
                                       4. Consecutive Systems                                  the development of the Stage 2 DBPR.                   drinking water regulations’’ (section
                                          The Stage 2 DBPR also contains                       These include the initial 1992–1994                    1412(b)(5)(A)). When establishing an
                                       provisions for regulating consecutive                   Microbial and Disinfection Byproduct                   MCL or treatment technique under this
                                       systems, defined in the Stage 2 DBPR as                 (M–DBP) stakeholder deliberations and                  authority, ‘‘the level or levels or
                                       public water systems that buy or                        EPA’s Stage 1 DBPR proposal (USEPA                     treatment techniques shall minimize the
                                       otherwise receive some or all of their                  1994); the 1996 Safe Drinking Water Act                overall risk of adverse health effects by
                                       finished water from another public                      (SDWA) Amendments; the 1996                            balancing the risk from the contaminant
                                       water system. Uniform regulation of                     Information Collection Rule; the 1998                  and the risk from other contaminants
                                       consecutive systems provided by the                     Stage 1 DBPR; new data, research, and                  the concentrations of which may be
                                       Stage 2 DBPR will ensure that                           analysis on disinfection byproduct                     affected by the use of a treatment
                                       consecutive systems deliver drinking                    (DBP) occurrence, treatment, and health                technique or process that would be
                                       water that meets applicable DBP                         effects since the Stage 1 DBPR; and the                employed to attain the maximum
                                       standards, thereby providing better,                    Stage 2 DBPR Microbial and                             contaminant level or levels’’ (section
                                       more equitable public health protection.                Disinfection Byproducts Federal                        1412(b)(5)(B)). In today’s rule, the
                                       More information on regulation of                       Advisory Committee. The following                      Agency is establishing MCLGs and
                                       consecutive systems can be found in                     sections provide summary background                    MCLs for certain DBPs, as described in
                                       Sections IV.B, IV.E, and IV.G.                          information on these subjects. For                     Section IV.
                                                                                               additional information, see the                           Finally, section 1412(b)(2)(C) of the
                                       C. Correction of § 141.132
                                                                                               proposed Stage 2 DBPR and supporting                   Act requires EPA to promulgate a Stage
                                         Section 553 of the Administrative                     technical material where cited (68 FR                  2 DBPR. Consistent with statutory
                                       Procedure Act, 5 U.S.C. 553(b)(B),                      49548, August 18, 2003) (USEPA                         provisions for risk balancing (section
                                       provides that, when an agency for good                  2003a).                                                1412(b)(5)(B)), EPA is finalizing the
                                       cause finds that notice and public                                                                             LT2ESWTR concurrently with the Stage
                                       procedure are impracticable,                            A. Statutory Requirements and Legal
                                                                                                                                                      2 DBPR to ensure simultaneous
                                       unnecessary, or contrary to the public                  Authority
                                                                                                                                                      protection from microbial and DBP
                                       interest, the agency may issue a rule                     The SDWA, as amended in 1996,                        risks.
                                       without providing prior notice and an                   authorizes EPA to promulgate a national
                                                                                                                                                      B. What is the Regulatory History of the
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                                       opportunity for public comment. In                      primary drinking water regulation
                                       addition to promulgating the Stage 2                    (NPDWR) and publish a maximum                          Stage 2 DBPR and How Were
                                       regulations, this rule also makes a minor               contaminant level goal (MCLG) for any                  Stakeholders Involved?
                                       correction to the National Primary                      contaminant the Administrator                            This section first summarizes the
                                       Drinking Water Regulations, specifically                determines ‘‘may have an adverse effect                existing regulations aimed at controlling

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                                       levels of DBPs in drinking water. The                   EPA finalized the Interim Enhanced                     calculation to a locational running
                                       Stage 2 DBPR establishes regulatory                     Surface Water Treatment Rule (63 FR                    annual average (LRAA) calculation. In
                                       requirements beyond these rules that                    69477, December 16, 1998) (USEPA                       the first phase, systems would continue
                                       target high risk systems and provide for                1998b) at the same time as the Stage 1                 to comply with the Stage 1 DBPR MCLs
                                       more equitable protection from DBPs                     DBPR to ensure simultaneous                            as RAAs and, at the same time, comply
                                       across the entire distribution system.                  compliance and address risk tradeoff                   with MCLs of 0.120 mg/L for TTHM and
                                       Next, this section summarizes the                       issues. Both rules were products of                    0.100 mg/L for HAA5 calculated as
                                       extensive stakeholder involvement in                    extensive Federal Advisory Committee                   LRAAs. RAA calculations average all
                                       the development of the Stage 2 DBPR.                    deliberations and final consensus                      samples collected within a distribution
                                                                                               recommendations in 1997.                               system over a one-year period, but
                                       1. Total Trihalomethanes Rule
                                                                                               3. Stakeholder Involvement                             LRAA calculations average all samples
                                          The first rule to regulate DBPs was
                                                                                                                                                      taken at each individual sampling
                                       promulgated on November 29, 1979.                          a. Federal Advisory Committee
                                                                                                                                                      location in a distribution system during
                                       The Total Trihalomethanes Rule (44 FR                   process. EPA reconvened the M-DBP
                                       68624, November 29, 1979) (USEPA                        Advisory Committee in March 1999 to                    a one-year period. Systems would also
                                       1979) set an MCL of 0.10 mg/L for total                 develop recommendations on issues                      carry out an Initial Distribution System
                                       trihalomethanes (TTHM). Compliance                      pertaining to the Stage 2 DBPR and                     Evaluation (IDSE) to select compliance
                                       was based on the running annual                         LT2ESWTR. The Stage 2 M-DBP                            monitoring sites that reflect higher
                                       average (RAA) of quarterly averages of                  Advisory Committee consisted of 21                     TTHM and HAA5 levels occurring in
                                       all samples collected throughout the                    organizational members representing                    the distribution system. The second
                                       distribution system. This TTHM                          EPA, State and local public health and                 phase of compliance would require
                                       standard applied only to community                      regulatory agencies, local elected                     MCLs of 0.080 mg/L for TTHM and
                                       water systems using surface water and/                  officials, Native American Tribes, large               0.060 mg/L for HAA5, calculated as
                                       or ground water that served at least                    and small drinking water suppliers,                    LRAAs at individual monitoring sites
                                       10,000 people and added a disinfectant                  chemical and equipment manufacturers,                  identified through the IDSE. The first
                                       to the drinking water during any part of                environmental groups, and other                        phase has been dropped in the final
                                       the treatment process.                                  stakeholders. Technical support for the                rule, as discussed in section IV.C.
                                                                                               Advisory Committee’s discussions was                     The Agreement in Principle also
                                       2. Stage 1 Disinfectants and Disinfection
                                                                                               provided by a technical working group                  provided recommendations for
                                       Byproducts Rule
                                                                                               established by the Advisory Committee.                 simultaneous compliance with the
                                          The Stage 1 DBPR, finalized in 1998                  The Advisory Committee held ten                        LT2ESWTR so that the reduction of
                                       (USEPA 1998a), applies to all                           meetings from September 1999 to July
                                       community and nontransient                                                                                     DBPs does not compromise microbial
                                                                                               2000, which were open to the public,                   protection. The complete text of the
                                       noncommunity water systems that add                     with an opportunity for public comment
                                       a chemical disinfectant to water. The                                                                          Agreement in Principle (USEPA 2000a)
                                                                                               at each meeting.
                                       rule established maximum residual                                                                              can be found online at
                                                                                                  The Advisory Committee carefully
                                       disinfectant level goals (MRDLGs) and                   considered extensive new data on the                   www.regulations.gov.
                                       enforceable maximum residual                            occurrence and health effects of DBPs,                   b. Other outreach processes. EPA
                                       disinfectant level (MRDL) standards for                 as well as costs and potential impacts                 worked with stakeholders to develop
                                       three chemical disinfectants—chlorine,                  on public water systems. In addition,                  the Stage 2 DBPR through various
                                       chloramine, and chlorine dioxide;                       they considered risk tradeoffs associated              outreach activities other than the M-
                                       maximum contaminant level goals                         with treatment changes. Based upon this                DBP Federal Advisory Committee
                                       (MCLGs) for three trihalomethanes                       detailed technical evaluation, the                     process. The Agency consulted with
                                       (THMs), two haloacetic acids (HAAs),                    committee concluded that a targeted                    State, local, and Tribal governments; the
                                       bromate, and chlorite; and enforceable                  protective public health approach                      National Drinking Water Advisory
                                       maximum contaminant level (MCL)                         should be taken to address exposure to                 Committee (NDWAC); the Science
                                       standards for TTHM, five haloacetic                     DBPs beyond the requirements of the                    Advisory Board (SAB); and Small Entity
                                       acids (HAA5), bromate (calculated as                    Stage 1 DBPR. While there had been                     Representatives (SERs) and small
                                       running annual averages (RAAs)), and                    substantial research to date, the                      system operators (as part of an Agency
                                       chlorite (based on daily and monthly                    Advisory Committee also concluded                      outreach initiative under the Regulatory
                                       sampling). The Stage 1 DBPR uses                        that significant uncertainty remained                  Flexibility Act). Section VII includes a
                                       TTHM and HAA5 as indicators of the                      regarding the risk associated with DBPs                complete description of the many
                                       various DBPs that are present in                        in drinking water. After reaching these                stakeholder activities which contributed
                                       disinfected water. Under the Stage 1                    conclusions, the Advisory Committee                    to the development of the Stage 2 DBPR.
                                       DBPR, water systems that use surface                    developed an Agreement in Principle
                                       water or ground water under the direct                  (65 FR 83015, December 29, 2000)                         Additionally, EPA posted a pre-
                                       influence of surface water and use                      (USEPA 2000a) that laid out their                      proposal draft of the Stage 2 DBPR
                                       conventional filtration treatment are                   consensus recommendations on how to                    preamble and regulatory language on an
                                       required to remove specified                            further control DBPs in public water                   EPA Internet site on October 17, 2001.
                                       percentages of organic materials,                       systems, which are reflected in today’s                This public review period allowed
                                       measured as total organic carbon (TOC),                 final rule.                                            readers to comment on the Stage 2
                                       that may react with disinfectants to form                  In the Agreement in Principle, the                  DBPR’s consistency with the Agreement
                                       DBPs. Removal is achieved through                       Advisory Committee recommended                         in Principle of the Stage 2 M-DBP
                                       enhanced coagulation or enhanced                        maintaining the MCLs for TTHM and                      Advisory Committee. EPA received
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                                       softening, unless a system meets one or                 HAA5 at 0.080 mg/L and 0.060 mg/L,                     important suggestions on this pre-
                                       more alternative compliance criteria.                   respectively, but changing the                         proposal draft from 14 commenters,
                                          The Stage 1 DBPR was one of the first                compliance calculation in two phases to                which included public water systems,
                                       rules to be promulgated under the 1996                  facilitate systems moving from the                     State governments, laboratories, and
                                       SDWA Amendments (USEPA 1998a).                          running annual average (RAA)                           other stakeholders.

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                                       C. Public Health Concerns to be                         formation within and between water                     weight of evidence involves
                                       Addressed                                               systems.                                               considerations of the quality and
                                                                                                 THMs and HAAs are widely occurring                   adequacy of data and consistency of
                                         EPA is promulgating the Stage 2 rule
                                                                                               classes of DBPs formed during                          responses. These factors are not scored
                                       to reduce the potential risks of cancer
                                                                                               disinfection with chlorine and                         mechanically by adding pluses and
                                       and reproductive and developmental
                                                                                               chloramine. The four THMs (TTHM)                       minuses; they are judged in
                                       health effects from DBPs. In addition,
                                                                                               and five HAAs (HAA5) measured and                      combination.
                                       the provisions of the Stage 2 DBPR
                                                                                               regulated in the Stage 2 DBPR act as                      • Criteria for determining ‘causality’
                                       provide for more equitable public health
                                                                                               indicators for DBP occurrence. There are               include consistency, strength, and
                                       protection. Sections C and D describe
                                                                                               other known DBPs in addition to a                      specificity of association, a temporal
                                       the general basis for this public health
                                                                                               variety of unidentified DBPs present in                relationship, a biological gradient (dose-
                                       concern through reviewing information                   disinfected water. THMs and HAAs                       response relationship), biological
                                       in the following areas: the health effects              typically occur at higher levels than                  plausibility, coherence with multiple
                                       associated with DBPs, DBP occurrence,                   other known and unidentified DBPs                      lines of evidence, evidence from human
                                       and the control of DBPs.                                (McGuire et al. 2002; Weinberg et al.                  populations, and information on agent’s
                                       1. What Are DBPs?                                       2002). The presence of TTHM and                        structural analogues (USEPA 2005i).
                                                                                               HAA5 is representative of the                          Additional considerations for individual
                                          Chlorine has been widely used to kill
                                                                                               occurrence of many other chlorination                  study findings include reliable exposure
                                       disease-causing microbes in drinking
                                                                                               DBPs; thus, a reduction in the TTHM                    data, statistical power and significance,
                                       water. The addition of chlorine in PWSs
                                                                                               and HAA5 generally indicates an overall                and freedom from bias and
                                       across the U.S. to kill microbial
                                                                                               reduction of DBPs.                                     confounding.
                                       pathogens in the water supply has been                                                                            • The term ‘hazard’ describes not a
                                       cited as one of the greatest public health              2. DBP Health Effects                                  definitive conclusion, but the possibility
                                       advances of the twentieth century                          Since the mid 1980’s, epidemiological               that a health effect may be attributed to
                                       (Okun 2003). For example, during the                    studies have supported a potential                     a certain exposure, in this case
                                       decade 1880–1890, American cities                       association between bladder cancer and                 chlorinated water. Analyses done for the
                                       experienced an average mortality rate of                chlorinated water and possibly also                    Stage 2 DBPR follow the 1999 EPA
                                       58 per 100,000 from typhoid, which was                  with colon and rectal cancers. In                      Proposed Guidelines for Carcinogenic
                                       commonly transmitted through                            addition, more recent health studies                   Risk Assessment (USEPA 1999a). In
                                       contaminated water. By 1938, this rate                  have reported potential associations                   March 2005, EPA updated and finalized
                                       had fallen to 0.67 deaths per 100,000,                  between chlorinated drinking water and                 the Cancer Guidelines and a
                                       largely due to improved treatment of                    reproductive and developmental health                  Supplementary Children’s Guidance,
                                       drinking water (Blake 1956).                            effects.                                               which include new considerations on
                                          During the disinfection process,                        Based on a collective evaluation of                 mode of action for cancer risk
                                       organic and inorganic material in source                both the human epidemiology and                        determination and additional potential
                                       waters can combine with chlorine and                    animal toxicology data on cancer and                   risks due to early childhood exposure
                                       certain other chemical disinfectants to                 reproductive and developmental health                  (USEPA 2005i; USEPA 2005j).
                                       form DBPs. More than 260 million                        effects discussed below and in                         Conducting the cancer evaluation using
                                       people in the U.S. are exposed to                       consideration of the large number of                   the 2005 Cancer Guidelines would not
                                       disinfected water and DBPs (USEPA                       people exposed to chlorinated                          result in any change from the existing
                                       2005a). Although chlorine is the most                   byproducts in drinking water (more                     analysis. With the exception of
                                       commonly applied disinfectant, other                    than 260 million), EPA concludes that                  chloroform, no mode of action has been
                                       disinfectants, including ozone, chlorine                (1) new cancer data since Stage 1                      established for other specific regulated
                                       dioxide, chloramine, and ultraviolet                    strengthen the evidence of a potential                 DBPs. Although some of the DBPs have
                                       radiation, are in use. In combination                   association of chlorinated water with                  given mixed mutagenicity and
                                       with these, all surface water systems                   bladder cancer and suggests an                         genotoxicity results, having a positive
                                       must also use either chlorine or                        association for colon and rectal cancers,              mutagenicity study does not necessarily
                                       chloramine to maintain a disinfectant                   (2) current reproductive and                           mean that a chemical has a mutagenic
                                       residual in their distribution system.                  developmental health effects data do not               mode of action. The extra factor of
                                       The kind of disinfectant used can                       support a conclusion at this time as to                safety for children’s health protection
                                       produce different types and levels of                   whether exposure to chlorinated                        does not apply because the new
                                       disinfectant byproducts in the drinking                 drinking water or disinfection                         Supplementary Children’s Guidance
                                       water.                                                  byproducts causes adverse                              requires application of the children’s
                                          Many factors affect the amount and                   developmental or reproductive health                   factor only when a mutagenic mode of
                                       kinds of DBPs in drinking water. Areas                  effects, but do support a potential health             action has been identified.
                                       in the distribution system that have had                concern, and (3) the combined health                      a. Cancer health effects. The following
                                       longer contact time with chemical                       data indicate a need for public health                 section briefly discusses cancer
                                       disinfectants tend to have higher levels                protection beyond that provided by the                 epidemiology and toxicology
                                       of DBPs, such as sites farther from the                 Stage 1 DBPR.                                          information EPA analyzed and some
                                       treatment plant, dead ends in the                          This section summarizes the key                     conclusions of these studies and reports.
                                       system, and small diameter pipes. The                   information in the areas of cancer,                    Further discussion of these studies and
                                       makeup and source of the water also                     reproductive, and developmental health                 EPA’s conclusions can be found in the
                                       affect DBP formation. Different types of                studies that EPA used to arrive at these               proposed Stage 2 DBPR (USEPA 2003a)
                                       organic and inorganic material will form                conclusions. Throughout this writeup,                  and the Economic Analysis for the Final
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                                       different types and levels of DBPs. Other               EPA uses ‘weight of evidence,’                         Stage 2 Disinfectants and Disinfection
                                       factors, such as water temperature,                     ‘causality,’ and ‘hazard’ as follows:                  Byproducts Rule (Economic Analysis
                                       season, pH, and location within the                        • A ‘weight of evidence’ evaluation is              (EA)) (USEPA 2005a).
                                       water purification process where                        a collective evaluation of all pertinent                  Human epidemiology studies and
                                       disinfectants are added, can affect DBP                 information. Judgement about the                       animal toxicology studies have

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                                       examined associations between                            ascertainment of cause of the cancer,                  surface waters. The database of studies
                                       chlorinated drinking water or DBPs and                   and reduction of potential selection bias              on colon and rectal cancers continues to
                                       cancer. While EPA cannot conclude                        in case-control and cohort studies (by                 support a possible association, but
                                       there is a causal link between exposure                  having comparable cases and controls                   evidence remains mixed. For colon
                                       to chlorinated surface water and cancer,                 and by limiting loss to follow-up).                    cancer, one newer study supports the
                                       EPA believes that the available research                 Epidemiology studies provide extremely                 evidence of an association (King et al.
                                       indicates a potential association                        useful information on human exposure                   2000a) while others showed
                                       between bladder cancer and exposure to                   to chlorinated water, which                            inconsistent findings (Hildesheim et al.
                                       chlorinated drinking water or DBPs.                      complement single chemical, high dose                  1998; Yang et al. 1998). Rectal cancer
                                       EPA also believes the available research                 animal data.                                           studies are also mixed. Hildesheim et al.
                                       suggests a possible association between                     In the Stage 1 DBPR, EPA concluded
                                                                                                                                                       (1998) and Yang et al. (1998) support an
                                       rectal and colon cancers and exposure                    that the epidemiological evidence
                                                                                                                                                       association with rectal cancer while
                                       to chlorinated drinking water or DBPs.                   suggested a potential increased risk for
                                                                                                bladder cancer. Some key studies EPA                   King et al. (2000a) did not. A review of
                                       This is based on EPA’s evaluation of all
                                                                                                considered for Stage 1 include Cantor et               colon and rectal cancer concluded
                                       available cancer studies. The next two
                                       sections focus on studies published                      al. (1998), Doyle et al. (1997), Freedman              evidence was inconclusive but that
                                       since the Stage 1 DBPR. Conclusions are                  et al. (1997), King and Marrett (1996),                there was a stronger association for
                                       based on the research as a whole.                        McGeehin et al. (1993), Cantor et al.                  rectal cancer and chlorination DBPs
                                          i. Epidemiology. A number of                          (1987), and Cantor et al. (1985). Several              than for colon cancer (Mills et al. 1998).
                                       epidemiological studies have been                        studies published since the Stage 1                    The WHO (2000) review reported that
                                       conducted to investigate the                             DBPR continue to support an                            studies showed weak to moderate
                                       relationship between exposure to                         association between increased risk of                  associations with colon and rectal
                                       chlorinated drinking water and various                   bladder cancer and exposure to                         cancers and chlorinated surface water or
                                       cancers. These studies contribute to the                 chlorinated surface water (Chevrier et                 THMs but that evidence is inadequate to
                                       overall evidence on potential human                      al. 2004; Koivusalo et al. 1998; Yang et               evaluate these associations.
                                       health hazards from exposure to                          al. 1998). One study found no effects on                  Recent studies on kidney, brain, and
                                       chlorinated drinking water.                              a biomarker of genotoxicity in urinary                 lung cancers and DBP exposure support
                                          Epidemiology studies provide useful                   bladder cells from TTHM exposure                       a possible association (kidney: Yang et
                                       health effects information because they                  (Ranmuthugala et al. 2003).                            al. 1998, Koivusalo et al. 1998; brain:
                                       reflect human exposure to a drinking                     Epidemiological reviews and meta-
                                       water DBP mixture through multiple                                                                              Cantor et al. 1999; lung: Yang et al.
                                                                                                analyses generally support the
                                       routes of intake such as ingestion,                                                                             1998). However, so few studies have
                                                                                                possibility of an association between
                                       inhalation and dermal absorption. The                    chlorinated water or THMs and bladder                  examined these endpoints that
                                       greatest difficulty with conducting                      cancer (Villanueva et al. 2004;                        definitive conclusions cannot be made.
                                       cancer epidemiology studies is the                       Villanueva et al. 2003; Villanueva et al.              Studies on leukemia found little or no
                                       length of time between exposure and                      2001; Mills et al. 1998). The World                    association with DBPs (Infante-Rivard et
                                       effect. Higher quality studies have                      Health Organization (WHO 2000) found                   al. 2002; Infante-Rivard et al. 2001). A
                                       adequately controlled for confounding                    data inconclusive or insufficient to                   recent study did not find an association
                                       and have limited the potential for                       determine causality between                            between pancreatic cancer and DBPs
                                       exposure misclassification, for example,                 chlorinated water and any health                       (Do et al. 2005). A study researching
                                       using DBP levels in drinking water as                    endpoint, although they concluded that                 multiple cancer endpoints found an
                                       the exposure metric as opposed to type                   the evidence is better for bladder cancer              association between THM exposure and
                                       of source water. Study design                            than for other cancers.                                all cancers when grouped together
                                       considerations for interpreting cancer                      In the Stage 1 DBPR, EPA concluded                  (Vinceti et al. 2004). More details on the
                                       epidemiology data include sufficient                     that early studies suggested a small                   cancer epidemiology studies since the
                                       follow-up time to detect disease                         possible increase in rectal and colon                  Stage 1 DBPR are outlined in Table II.D–
                                       occurrence, adequate sample size, valid                  cancers from exposure to chlorinated                   1.

                                                         TABLE II.D–1.—SUMMARY OF CANCER EPIDEMIOLOGY STUDIES REVIEWED FOR STAGE 2 DBPR
                                                              Study type              Exposure(s) studied                                                           Findings

                                       Do et al. 2005      Case-control         Estimated chlorinated DBPs,         Pancreatic can-       No association was found between pancreatic cancer and
                                                             study in             chloroform, BDCM con-               cer.                  exposure to chlorinated DBPs, chloroform, or BDCM.
                                                             Canada,              centrations.
                                       Chevrier et al.     Case-control         Compared THM levels, dura-          Bladder cancer.       A statistically significant decreased risk of bladder cancer
                                         2004..             study in              tion of exposure, and 3                                   was found as duration of exposure to ozonated water in-
                                                            France,               types of water treatment                                  creased. This was evident with and without adjustment
                                                            1985–1987.            (ozonation, chlorination,                                 for other exposure measures. A small association was
                                                                                  ozonation/chlorination).                                  detected for increased bladder cancer risk and duration
                                                                                                                                            of exposure to chlorinated surface water and with the es-
                                                                                                                                            timated THM content of the water, achieving statistical
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                                                                                                                                            significance only when adjusted for duration of ozonated
                                                                                                                                            water exposures. Effect modification by gender was
                                                                                                                                            noted in the adjusted analyses.

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                                               TABLE II.D–1.—SUMMARY OF CANCER EPIDEMIOLOGY STUDIES REVIEWED FOR STAGE 2 DBPR—Continued
                                                              Study type              Exposure(s) studied                                                           Findings

                                       Vinceti et al.      Retrospective        Standardized mortality ratios                   Mortality ratio from all cancers showed a statistically signifi-
                                                                                                                    15 cancers in-
                                         2004.              cohort study          from all causes vs. cancer                      cant small increase for males consuming drinking water
                                                                                                                      cluding colon,
                                                            in Italy,             for consumers drinking              rectum, and with high THMs. For females, an increased mortality ratio
                                                            1987–1999.            water with high THMs.               bladder.    for all cancers was seen but was not statistically signifi-
                                                                                                                                  cant. Stomach cancer in men was the only individual
                                                                                                                                  cancer in which a statistically significant excess in mor-
                                                                                                                                  tality was detected for consumption of drinking water with
                                                                                                                                  high THMs.
                                       Ranmuthugala        Cohort study         Estimated dose of TTHM,        Frequency of     Relative risk estimates for DNA damage to bladder cells for
                                         et al. 2003.        in 3 Aus-            chloroform, and bromoform      micronuclei in   THM dose metrics were near 1.0. The study provides no
                                                             tralian com-         from routinely-collected       urinary blad-    evidence that THMs are associated with DNA damage to
                                                             munities,            THM measurements and           der epithelial   bladder epithelial cells, and dose-response patterns were
                                                             1997.                fluid intake diary.            cells.           not detected.
                                       Infante-Rivard      Population-          Estimated prenatal and post-   Acute            Data are suggestive, but imprecise, linking DNA variants
                                          et al. 2002.       based case-          natal exposure to THMs         lymphoblastic    with risk of acute lymphoblastic leukemia associated with
                                                             control study        and polymorphisms in two       leukemia.        drinking water DBPs. The number of genotyped subjects
                                                             in Quebec,           genes.                                          for GSTT1 and CYP2E1 genes was too small to be con-
                                                             1980–1993.                                                           clusive.
                                       Infante-Rivard      Population-          Compared water chlorination    Acute            No increased risk for lymphoblastic leukemia was observed
                                          et al. 2001.       based case-          (never, sometimes, always)     lymphoblastic    for prenatal exposure at average levels of TTHMs, met-
                                                             control study        and exposure to TTHMs,         leukemia.        als or nitrates. However, a non-statistically significant,
                                                             in Quebec,           metals, and nitrates.                           small increased risk was seen for postnatal cumulative
                                                             1980–1993.                                                           exposure to TTHMs and chloroform (both at above the
                                                                                                                                  95th exposure percentile of the distribution for cases and
                                                                                                                                  controls), for zinc, cadmium, and arsenic, but not other
                                                                                                                                  metals or nitrates.
                                       King et al.         Population-          Compared source of drinking Colon and rec-      Colon cancer risk was statistically associated with cumu-
                                         2000a.              based case-          water and chlorination sta-    tal cancer.      lative long term exposure to THMs, chlorinated surface
                                                             control study        tus. Estimated TTHM lev-                        water, and tap water consumption metrics among males
                                                             in southern          els, duration of exposure,                      only. Exposure-response relationships were evident for
                                                             Ontario,             and tap water consumption.                      exposure measures combining duration and THM levels.
                                                             1992–1994.                                                           Associations between the exposure measures and rectal
                                                                                                                                  cancer were not observed for either gender.
                                       Cantor et al.       Population-          Compared level and duration Brain cancer .... Among males, a statistically significant increased risk of
                                         1999.               based case-          of THM exposure (cumu-                          brain cancer was detected for duration of chlorinated
                                                             control study        lative and average), source                     versus non-chlorinated source water, especially among
                                                             in Iowa,             of water, chlorination, and                     high-level consumers of tap water. An increased risk of
                                                             1984–1987.           water consumption.                              brain cancer for high water intake level was found in
                                                                                                                                  men. No associations were found for women for any of
                                                                                                                                  the exposure metrics examined.
                                       Cantor et al.       Population-          Compared level and duration Bladder cancer A statistically significant positive association between risk
                                         1998.               based case-          of THM exposure (cumu-                          of bladder cancer and exposure to chlorinated ground-
                                                             control study        lative and average), source                     water or surface water reported for men and for smokers,
                                                             in Iowa,             of water, chlorination, and                     but no association found for male/female non-smokers,
                                                             1986–1989.           water consumption.                              or for women overall. Limited evidence was found for an
                                                                                                                                  association between tapwater consumption and bladder
                                                                                                                                  cancer risk. Suggestive evidence existed for exposure-re-
                                                                                                                                  sponse effects of chlorinated water and lifetime THM
                                                                                                                                  measures on bladder cancer risk.
                                       Hildesheim et       Population-          Compared level and duration Colon and rec-      Increased risks of rectal cancer was associated with dura-
                                         al. 1998.           based case-          of THM exposure (cumu-         tal cancer.      tion of exposure to chlorinated surface water and any
                                                             control study        lative and average), source                     chlorinated water, with evidence of an exposure-re-
                                                             in Iowa,             of water, chlorination, and                     sponse relationship. Risk of rectal cancer is statistically
                                                             1986–1989.           water consumption.                              significant increased with >60 years lifetime exposure to
                                                                                                                                  THMs in drinking water, and risk increased for individuals
                                                                                                                                  with low dietary fiber intake. Risks were similar for men
                                                                                                                                  and women and no effects were observed for tapwater
                                                                                                                                  measures. No associations were detected for water ex-
                                                                                                                                  posure measures and risk of colon cancer.
                                       Koivusalo et        Population-          Estimated residential duration Bladder and      Drinking water mutagenicity was associated with a small,
                                         al. 1998.           based case-          of exposure and level of       kidney cancer.   statistically significant, exposure-related excess risk for
                                                             control study        drinking water mutagenicity.                    kidney and bladder cancers among men; weaker asso-
                                                             in Finland,                                                          ciations were detected for mutagenic water and bladder
                                                             1991–1992.                                                           or kidney cancer among women. The effect of mutage-
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                                                                                                                                  nicity on bladder cancer was modified by smoking status,
                                                                                                                                  with an increased risk among non-smokers.

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                                               TABLE II.D–1.—SUMMARY OF CANCER EPIDEMIOLOGY STUDIES REVIEWED FOR STAGE 2 DBPR—Continued
                                                               Study type              Exposure(s) studied                                                           Findings

                                       Yang et al.          Cross-sec-           Examined residence in               Cancer of rec-   Residence in chlorinating municipalities (vs. non-
                                         1998.                tional study         chlorinated (mainly surface         tum, lung,       chlorinating) was statistically significantly associated with
                                                              in Taiwan,           water sources) relative to          bladder, kid-    the following types of cancer in both males and females:
                                                              1982–1991.           non-chlorinated (mainly pri-        ney, colon,      rectal, lung, bladder, and kidney cancer. Liver cancer
                                                                                   vate well) water.                   and 11 others.   and all cancers were also statistically significantly ele-
                                                                                                                                        vated in chlorinated towns for males only. Mortality rates
                                                                                                                                        for cancers of the esophagus, stomach, colon, pancreas,
                                                                                                                                        prostate, brain, breast, cervix uteri and uterus, and ovary
                                                                                                                                        were comparable for chlorinated and non-chlorinated res-
                                       Doyle et al.         Prospective          Examined chloroform levels          Colon, rectum,   Statistically significant increased risk of colon cancer,
                                         1997.                cohort study         and source of drinking              bladder, and     breast cancer and all cancers combined was observed
                                                              in Iowa,             water.                              8 other can-     for women exposed to chloroform in drinking water, with
                                                              1987–1993.                                               cers in          evidence of exposure-response effects. No associations
                                                                                                                       women.           were detected between chloroform and bladder, rectum,
                                                                                                                                        kidney, upper digestive organs, lung, ovary, endo-
                                                                                                                                        metrium, or breast cancers, or for melanomas or non-
                                                                                                                                        Hodgkin’s lymphoma. Surface water exposure (compared
                                                                                                                                        to ground water users) was also a significant predictor of
                                                                                                                                        colon and breast cancer risk.
                                       Freedman et          Population-          Estimated duration of expo-         Bladder cancer There was a weak association between bladder cancer risk
                                         al. 1997.            based case-          sure to chlorinated water.                           and duration of exposure to municipal water for male cig-
                                                              control study        Compared exposure to                                 arette smokers, as well as an exposure-response rela-
                                                              in Maryland,         chlorinated municipal water                          tionship. No association was seen for those with no his-
                                                              1975–1992.           (yes/no).                                            tory of smoking, suggesting that smoking may modify a
                                                                                                                                        possible effect of chlorinated surface water on the risk of
                                                                                                                                        bladder cancer.
                                       King and        Case-control              Compared source of drinking         Bladder cancer Statistically significant associations were detected for blad-
                                         Marrett 1996.  study in On-               water and chlorination sta-                          der cancer and chlorinated surface water, duration or
                                                        tario, Can-                tus. Estimated TTHM lev-                             concentration of THM levels and tap water consumption
                                                        ada, 1992–                 els, duration of exposure,                           metrics. Population attributable risks were estimated at
                                                         1994.                     and tap water consumption.                           14 to 16 percent. An exposure-response relationship was
                                                                                                                                        observed for estimated duration of high THM exposures
                                                                                                                                        and risk of bladder cancer.
                                       McGeehin et          Population-          Compared source of drinking         Bladder cancer Statistically significant associations were detected for blad-
                                        al. 1993.             based case-          water, water treatment, and                          der cancer and duration of exposure to chlorinated sur-
                                                              control study        tap water versus bottled                             face water. The risk was similar for males and females
                                                              in Colorado,         water. Estimated duration                            and among nonsmokers and smokers. The attributable
                                                              1990–1991.           of exposure to TTHMs and                             risk was estimated at 14.9 percent. High tap water intake
                                                                                   levels of TTHMs, nitrates,                           was associated with risk of bladder cancer in a expo-
                                                                                   and residual chlorine.                               sure-response fashion. No associations were detected
                                                                                                                                        between bladder cancer and levels of TTHMs, nitrates,
                                                                                                                                        and residual chlorine.
                                       Cantor et al.        Population-          Compared source of drinking         Bladder cancer Bladder cancer was statistically associated with duration of
                                         1987 (and            based case-          water. Estimated total bev-                          exposure to chlorinated surface water for women and
                                         Cantor et al.        control study        erage and tap water con-                             nonsmokers of both sexes. The largest risks were seen
                                         1985).               in 10 areas          sumption and duration of                             when both exposure duration and level of tap water in-
                                                              of the U.S.,         exposure.                                            gestion were combined. No association was seen for
                                                              1977–1978.                                                                total beverage consumption.
                                       Villanueva et        Review and           Individual-based exposure           Bladder cancer        The meta-analysis suggests that risk of bladder cancer in
                                          al. 2004.          meta-anal-            estimates to THMs and                                     men increases with long-term exposure to TTHMs. An
                                                             ysis of 6             water consumption over a                                  exposure-response pattern was observed among men
                                                             case-control          40-year period.                                           exposed to TTHMs, with statistically significant risk seen
                                                             studies.                                                                        at exposures higher than 50 ug/L. No association be-
                                                                                                                                             tween TTHMs and bladder cancer was seen for women.
                                       Villanueva et        Review and           Compared source of water            Bladder cancer        The meta-analysis findings showed a moderate excess risk
                                          al. 2003           meta-anal-            and estimated duration of                                 of bladder cancer attributable to long-term consumption
                                          (and Goebell       ysis of 6             exposure to chlorinated                                   of chlorinated drinking water for both genders, particu-
                                          et al. 2004).      case-control          drinking water.                                           larly in men. Statistically significance seen with men and
                                                             studies and                                                                     combined both sexes. The risk was higher when expo-
                                                             2 cohort                                                                        sure exceeded 40 years.
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                                                  TABLE II.D–1.—SUMMARY OF CANCER EPIDEMIOLOGY STUDIES REVIEWED FOR STAGE 2 DBPR—Continued
                                                                   Study type                    Exposure(s) studied                                                                     Findings

                                       Villanueva et            Qualitative re-           Compared exposure to TTHM                        Cancer of blad-     Review found that although results for cancer studies var-
                                          al. 2001.              view of 31                 levels, mutagenic drinking                       der, colon,         ied and were not always statistically significant, evidence
                                                                 cancer stud-               water, water consumption,                        rectum, and 5       for bladder cancer is strongest, and all 10 of the bladder
                                                                 ies.                       source water, types of dis-                      other can-          cancer studies showed increased cancer risks with in-
                                                                                            infection (chlorination and                      cers..              gestion of chlorinated water. The authors felt associa-
                                                                                            chloramination), and resi-                                           tions with chlorinated water and cancer of the colon, rec-
                                                                                            dence times.                                                         tum, pancreas, esophagus, brain, and other cancers
                                                                                                                                                                 were inconsistent.
                                       WHO 2000 .....           Qualitative re-           Various exposures to THMs.                       Various cancers     Studies reviewed reported weak to moderate increased rel-
                                                                 views of var-                                                                                   ative risks of bladder, colon, rectal, pancreatic, breast,
                                                                 ious studies                                                                                    brain or lung cancer associated with long-term exposure
                                                                 in Finland,                                                                                     to chlorinated drinking water. The authors felt evidence is
                                                                 U.S., and                                                                                       inconclusive for an association between colon cancer
                                                                 Canada.                                                                                         and long-term exposure to THMs; that evidence is insuffi-
                                                                                                                                                                 cient to evaluate a causal relationship between THMs
                                                                                                                                                                 and rectal, bladder, and other cancers. They found no
                                                                                                                                                                 association between THMs and increased risk of cardio-
                                                                                                                                                                 vascular disease.
                                       Mills et al.             Qualitative re-           Examined TTHM levels and                         Cancer of           Review suggests possible increases in risks of bladder
                                         1998.                   view of 22                 water consumption. Com-                          colon, rec-         cancer with exposure to chlorinated drinking water. The
                                                                 studies.                   pared source of water and                        tum, and            authors felt evidence for increased risk of colon and rec-
                                                                                            2 types of water treatment                       bladder.            tal cancers is inconclusive, though evidence is stronger
                                                                                            (chlorination and                                                    for rectal cancer.

                                         Overall, bladder cancer data provide                                  cancer toxicology and mode of action                         (USEPA 2001a), chlorine dioxide and
                                       the strongest basis for quantifying                                     studies completed since the Stage 1                          chlorite (USEPA 2000c), and bromate
                                       cancer risks from DBPs. EPA has chosen                                  DBPR was finalized in December 1998.                         (USEPA 2001b), and is currently
                                       this endpoint to estimate the primary                                      In support of this rule, EPA has                          reassessing TCAA.
                                       benefits of the Stage 2 DBPR (see                                       developed health criteria documents
                                                                                                               which summarize the available                                   Slope factors and risk concentrations
                                       Section VI).
                                         ii. Toxicology. Cancer toxicology                                     toxicology data for brominated THMs                          for BDCM, bromoform, DBCM and
                                       studies provide additional support that                                 (USEPA 2005b), brominated HAAs                               DCAA have been developed and are
                                       chlorinated water is associated with                                    (USEPA 2005c), MX (USEPA 2000b),                             listed in Table II.D–2. For BDCM,
                                       cancer. In general, EPA uses long term                                  MCAA (USEPA 2005d), and TCAA                                 bromoform, and DBCM, table values are
                                       toxicology studies that show a dose                                     (USEPA 2005e). The 2003 IRIS                                 derived from the brominated THM
                                       response to derive MCLGs and cancer                                     assessment of DCAA (USEPA 2003b)                             criteria document (USEPA 2005b),
                                       potency factors. Short term studies are                                 and an addendum (USEPA 2005k) also                           which uses IRIS numbers that have been
                                       used for hazard identification and to                                   provides analysis released after Stage 1.                    updated using the 1999 EPA Proposed
                                       design long term studies. Much of the                                   It summarizes information on exposure                        Guidelines for Carcinogenic Risk
                                       available cancer toxicology information                                 from drinking water and develops a                           Assessment (USEPA 1999a). For DCAA,
                                       was available for the Stage 1 DBPR, but                                 slope factor for DCAA. IRIS also has                         the values are derived directly from
                                       there have also been a number of new                                    toxicological reviews for chloroform                         IRIS.

                                                                                                     TABLE II.D–2.—QUANTIFICATION OF CANCER RISK
                                                                                                                                                             LED 10a                                 ED 10a

                                                                       Disinfection byproduct                                                    Slope              10 ¥6 Risk             Slope               10 ¥6 Risk
                                                                                                                                                 factor            concentration           factor             concentration
                                                                                                                                             (mg/kg/day)¥1            (mg/L)           (mg/kg/day) ¥1            (mg/L)

                                       Bromodichloromethane ....................................................................                        0.034                0.001               0.022                  0.002
                                       Bromoform .......................................................................................               0.0045                0.008              0.0034                   0.01
                                       Dibromochloromethane ....................................................................                         0.04               0.0009               0.017                  0.002
                                       Dichloroacetic Acid ..........................................................................                   0.048               0.0007              0.015 b              0.0023 b
                                          a LED
                                               10 is the lower 95% confidence bound on the (effective dose) ED10 value. ED10 is the estimated dose producing effects in 10% of ani-
                                          b The ED
                                                   10 risk factors for DCAA have been changed from those given in the comparable table in the proposed Stage 2 DBPR to correct for
                                       transcriptional errors.
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                                          More research on DBPs is underway                                    www.epa.gov/safewater/drink/                                 been completed on BDCM and chlorate.
                                       at EPA and other research institutions.                                 intro.html). Two-year bioassays by the                       The draft abstract on BDCM reported no
                                       Summaries of on-going studies may be                                    National Toxicology Program (NTP)                            evidence of carcinogenicity when
                                       found on EPA’s DRINK Web site (http://                                  released in abstract form have recently                      BDCM was administered via drinking

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                                       water (NTP 2005a). Another recent                       ability to detect statistically significant            endpoints (spontaneous abortion or
                                       study, a modified two-year bioassay on                  associations for small to moderate                     stillbirth) remains inconsistent as a
                                       BDCM in the drinking water, reported                    relative risk estimates. Small sample                  whole, there is suggestive evidence of
                                       little evidence of carcinogenicity                      sizes also result in imprecision around                an association between fetal loss and
                                       (George et al. 2002). In a previous NTP                 risk estimates reflected by wide                       chlorinated water or DBP exposure.
                                       study, tumors were observed, including                  confidence intervals. In addition to the               Various studies support the possibility
                                       an increased incidence of kidney, liver,                limitations of individual studies,                     that exposure to chlorinated water or
                                       and colon tumors, when BDCM was                         evaluating reproductive and                            DBPs is associated with decreased fetal
                                       administered at higher doses by gavage                  developmental epidemiology studies                     viability (Toledano et al. 2005; Dodds et
                                       in corn oil (NTP 1987). EPA will                        collectively is difficult because of the               al. 2004; King et al. 2000b; Dodds et al.
                                       examine new information on BDCM as                      methodological differences between                     1999; Waller et al. 1998; Aschengrau et
                                       it becomes available. In the chlorate                   studies and the wide variety of                        al. 1993; Aschengrau et al. 1989). Other
                                       draft abstract, NTP found some evidence                 endpoints examined. These factors may                  studies did not support an association
                                       that it may be a carcinogen (NTP 2004).                 contribute to inconsistencies in the                   (Bove et al. 1995) or reported
                                       Chlorate is a byproduct of hypochlorite                 scientific body of literature as noted                 inconclusive results (Savitz et al. 2005;
                                       and chlorine dioxide systems. A long-                   below.                                                 Swan et al. 1998; Savitz et al. 1995)
                                       term, two-year bioassay NTP study on                       More recent studies tend to be of                   between fetal viability and exposure to
                                       DBA is also complete but has not yet                    higher quality because of improved                     THMs or tapwater. A recent study by
                                       undergone peer review (NTP 2005b).                      exposure assessments and other                         King et al. (2005) found little evidence
                                          b. Reproductive and developmental                    methodological advancements. For                       of an association between stillbirths and
                                       health effects. Both human                              example, studies that use THM levels to                haloacetic acids after controlling for
                                       epidemiology studies and animal                         estimate exposure tend to be higher                    trihalomethane exposures, though non-
                                       toxicology studies have examined                        quality than studies that define                       statistically significant increases in
                                       associations between chlorinated                        exposure by source or treatment. These                 stillbirths were seen across various
                                       drinking water or DBPs and                              factors were taken into account by EPA                 exposure levels.
                                       reproductive and developmental health                   when comparing and making                                 Fetal malformations. A number of
                                       effects. Based on an evaluation of the                  conclusions on the reproductive and                    epidemiology studies have examined
                                       available science, EPA believes the data                developmental epidemiology literature.                 the relationship between fetal
                                       suggest that exposure to DBPs is a                      What follows is a summary of available                 malformations (such as neural tube, oral
                                       potential reproductive and                              epidemiology literature on reproductive                cleft, cardiac, or urinary defects, and
                                       developmental health hazard.                            and developmental endpoints such as                    chromosomal abnormalities) and
                                          The following section briefly                        spontaneous abortion, stillbirth, neural               chlorinated water or DBPs. It is difficult
                                       discusses the reproductive and                          tube and other birth defects, low birth                to assess fetal malformations in
                                       developmental epidemiology and                          weight, and intrauterine growth                        aggregate due to inconsistent findings
                                       toxicology information available to EPA.                retardation. Information is grouped,                   and disparate endpoints being examined
                                       Further discussion of these studies and                 where appropriate, into three categories               in the available studies. Some studies
                                       EPA’s conclusions can be found in the                   on fetal growth, viability, and                        support the possibility that exposure to
                                       proposed Stage 2 DBPR (USEPA 2003a)                     malformations, and reviews are                         chlorinated water or DBPs is associated
                                       and the Economic Analysis (USEPA                        described separately afterward. Table                  with various fetal malformations
                                       2005a).                                                 II.D–3 provides a more detailed                        (Cedergren et al. 2002; Hwang et al.
                                          i. Epidemiology. As discussed                        description of each study or review.                   2002; Dodds and King 2001; Klotz and
                                       previously, epidemiology studies have                      Fetal growth. Many studies looked for               Pyrch 1999; Bove et al. 1995;
                                       the strength of relating human exposure                 an association between fetal growth                    Aschengrau et al. 1993). Other studies
                                       to DBP mixtures through multiple                        (mainly small for gestational age, low                 found little evidence (Shaw et al. 2003;
                                       intake routes. Although the critical                    birth weight, and pre-term delivery) and                 ¨ ´
                                                                                                                                                      Kallen and Robert 2000; Dodds et al.
                                       exposure window for reproductive and                    chlorinated water or DBPs. The results                 1999; Shaw et al. 1991) or inconclusive
                                       developmental effects is much smaller                   from the collection of studies as a whole              results (Magnus et al. 1999) between
                                       than that for cancer (generally weeks                   are inconsistent. A number of studies                  chlorinated water or DBP exposure and
                                       versus years), exposure assessment is                   support the possibility that exposure to               fetal malformations. Birth defects most
                                       also a main limitation of reproductive                  chlorinated water or DBPs are                          consistently identified as being
                                       and developmental epidemiology                          associated with adverse fetal growth                   associated with DBPs include neural
                                       studies. Exposure assessment                            effects (Infante-Rivard 2004; Wright et                tube defects and urinary tract
                                       uncertainties arise from limited data on                                                  ¨ ´
                                                                                               al. 2004; Wright et al. 2003; Kallen and               malformations.
                                       DBP concentrations and maternal water                   Robert 2000; Gallagher et al. 1998;                       Other endpoints have also been
                                       usage and source over the course of the                 Kanitz et al. 1996; Bove et al. 1995;                  examined in recent epidemiology
                                       pregnancy. However, classification                      Kramer et al. 1992). Other studies                     studies. One study suggests an
                                       errors typically push the true risk                     showed mixed results (Porter et al.                    association between DBPs and
                                       estimate towards the null value (Vineis                 2005; Savitz et al. 2005; Yang 2004) or                decreased menstrual cycle length
                                       2004). According to Bove et al. (2002),                 did not provide evidence of an                         (Windham et al. 2003), which, if
                                       ‘‘Difficulties in assessing exposure may                association (Toledano et al. 2005;                     corroborated, could be linked to the
                                       result in exposure misclassification                    Jaakkola et al. 2001; Dodds et al. 1999;               biological basis of other reproductive
                                       biases that would most likely produce                   Savitz et al. 1995) between DBP                        endpoints observed. No association
                                       substantial underestimates of risk as                   exposure and fetal growth. EPA notes                   between THM exposure and semen
                                       well as distorted or attenuated                         that recent, higher quality studies                    quality was found (Fenster et al. 2003).
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                                       exposure-response trends.’’ Studies of                  provide some evidence of an increased                  More work is needed in both areas to
                                       rare outcomes (e.g., individual birth                   risk of small for gestational age and low              support these results.
                                       defects) often have limited statistical                 birth weight.                                             Reviews. An early review supported
                                       power because of the small number of                       Fetal viability. While the database of              an association between measures of fetal
                                       cases being examined. This limits the                   epidemiology studies for fetal loss                    viability and tap water (Swan et al.

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                                       1992). Three other reviews found data                     et al. (2000) concluded that the weight                        reproductive effects and drinking
                                       inadequate to support an association                      of evidence from epidemiology studies                          chlorinated water. Graves et al. (2001)
                                       between reproductive and                                  suggests that ‘‘DBPs are likely to be                          supports a possible association for fetal
                                       developmental health effects and THM                      reproductive toxicants in humans under                         growth but not fetal viability or
                                       exposure (Reif et al. 1996; Craun 1998;                   appropriate exposure conditions,’’ but                         malformations. More recently, Bove et
                                       WHO 2000). Mills et al. (1998)                            from a risk assessment perspective, data                       al. (2002) examined and supported an
                                       examined data on and found support for                    are primarily at the hazard                                    association between small for
                                       an association between fetal viability                    identification stage. Nieuwenhuijsen et                        gestational age, neural tube defects and
                                       and malformations and THMs. Another                       al. (2000) found some evidence for an                          spontaneous abortion endpoints and
                                       review presented to the Stage 2 MDBP                      association between fetal growth and                           DBPs. Following a meta-analysis on five
                                       FACA found some evidence for an                           THM exposure and concluded evidence                            malformation studies, Hwang and
                                       association with fetal viability and some                 for associations with other fetal                              Jaakkola (2003) concluded that there
                                       fetal malformations and exposure to                       endpoints is weak but gaining weight. A                        was evidence which supported
                                       DBPs but reported that the evidence was                   qualitative review by Villanueva et al.                        associations between DBPs and risk of
                                       inconsistent for these endpoints as well                  (2001) found evidence generally                                birth defects, especially neural tube
                                       as for fetal growth (Reif et al. 2000). Reif              supports a possible association between                        defects and urinary tract defects.

                                                              TABLE II.D–3.—SUMMARY OF REPRODUCTIVE/DEVELOPMENTAL EPIDEMIOLOGY STUDIES
                                         Author(s)              Study type                  Exposure(s) studied         Outcome(s) measured                                        Findings

                                       Porter et al.    Cross-sectional study in          Estimated THM and            Intrauterine growth re-                No consistent association or dose-response rela-
                                         2005.            Maryland, 1998–2002.              HAA exposure during           tardation.                            tionship was found between exposure to either
                                                                                            pregnancy.                                                          TTHM or HAA5 and intrauterine growth retar-
                                                                                                                                                                dation. Results suggest an increased risk of
                                                                                                                                                                intrauterine growth retardation associated with
                                                                                                                                                                TTHM and HAA5 exposure in the third tri-
                                                                                                                                                                mester, although only HAA5 results were sta-
                                                                                                                                                                tistically significant.
                                       Savitz et al.    Population-based pro-             Estimated TTHM, HAA9,        Early and late preg-                   No association with pregnancy loss was seen
                                         2005.            spective cohort study             and TOC exposures            nancy loss, preterm                    when looking at high exposure of TTHM com-
                                                          in three communities              during pregnancy. In-        birth, small for gesta-                pared to low exposure of TTHM. When exam-
                                                          around the U.S.,                  dices examined in-           tional age, and term                   ining individual THMs, a statistically significant
                                                          2000–2004.                        cluded concentration,        birth weight.                          association         was       found       between
                                                                                            ingested amount, ex-                                                bromodichloromethane (BDCM) and preg-
                                                                                            posure from show-                                                   nancy loss. A similar, non-statistically signifi-
                                                                                            ering and bathing,                                                  cant      association     was     seen    between
                                                                                            and an integration of                                               dibromochloromethane (DBCM) and preg-
                                                                                            all exposures com-                                                  nancy loss. Some increased risk was seen for
                                                                                            bined.                                                              losses at greater than 12 weeks’ gestation for
                                                                                                                                                                TTHM, BDCM, and TOX (total organic halide),
                                                                                                                                                                but most results generally did not provide sup-
                                                                                                                                                                port for an association. Preterm birth showed
                                                                                                                                                                a small inverse relationship with DBP expo-
                                                                                                                                                                sure (i.e. higher exposures showed less
                                                                                                                                                                preterm births), but this association was weak.
                                                                                                                                                                TTHM exposure of 80 ug/L was associated
                                                                                                                                                                with twice the risk for small for gestational age
                                                                                                                                                                during the third trimester and was statistically
                                       Toledano et      Large cross-sectional             Linked mother’s resi-        Stillbirth, low birth                  A significant association between TTHM and risk
                                         al. 2005.        study in England,                 dence at time of deliv-      weight.                                of stillbirth, low birth weight, and very low birth
                                                          1992–1998.                        ery to modeled esti-                                                weight was observed in one of the three re-
                                                                                            mates of TTHM levels                                                gions. When all three regions were combined,
                                                                                            in water zones.                                                     small, but non-significant, excess risks were
                                                                                                                                                                found between all three outcomes and TTHM
                                                                                                                                                                and chloroform. No associations were ob-
                                                                                                                                                                served between reproductive risks and BDCM
                                                                                                                                                                or total brominated THMs.
                                       Dodds et al.     Population-based case-            Estimated THM and            Stillbirth .........................   A statistically significant association was ob-
                                         2004 (and        control study in Nova             HAA exposure at resi-                                               served between stillbirths and exposure to
                                         King et al.      Scotia and Eastern                dence during preg-                                                  total THM, BDCM, and chloroform. Associa-
                                         2005).           Ontario, 1999–2001.               nancy. Linked water                                                 tions were also detected for metrics, which in-
                                                                                            consumption and                                                     corporated water consumption, showering and
                                                                                            showering/bathing to                                                bathing habits. Elevated relative risks were ob-
                                                                                            THM exposure.                                                       served for intermediate exposures for total
                                                                                                                                                                HAA and DCAA measures; TCAA and
                                                                                                                                                                brominated HAA exposures showed no asso-
wwhite on PROD1PC65 with RULES2

                                                                                                                                                                ciation. No statistically significant associations
                                                                                                                                                                or dose-response relationships between any
                                                                                                                                                                HAAs and stillbirth were detected after control-
                                                                                                                                                                ling for THM exposure.

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                                                       TABLE II.D–3.—SUMMARY OF REPRODUCTIVE/DEVELOPMENTAL EPIDEMIOLOGY STUDIES—Continued
                                         Author(s)              Study type                  Exposure(s) studied          Outcome(s) measured                                 Findings

                                       Infante-         Case-control study of             Estimated THM levels          Intrauterine growth re-         No associations were found between exposure
                                          Rivard          newborns in Montreal,             and water consump-             tardation.                     to THMs and intrauterine growth retardation.
                                          2004.           1998–2000.                        tion during pregnancy.                                        However, a significant effect was observed be-
                                                                                            Exposure from show-                                           tween THM exposure and intrauterine growth
                                                                                            ering and presence of                                         retardation for newborns with the CYP2E1
                                                                                            two genetic                                                   gene variant. Findings suggest that exposure
                                                                                            polymorphisms.                                                to THMs at the highest levels can affect fetal
                                                                                                                                                          growth but only in genetically susceptible
                                       Wright et al.    Large cross-sectional             Estimated maternal            Birth weight, small for         Statistically significant reductions in mean birth
                                        2004.             study: Massachusetts,             third-trimester expo-         gestational age,                weight were observed for BDCM, chloroform,
                                                          1995–1998.                        sures to TTHMs, chlo-         preterm delivery, ges-          and mutagenic activity. An exposure-response
                                                                                            roform, BDCM, total           tational age.                   relationship was found between THM expo-
                                                                                            HAAs, DCA, TCA, MX                                            sure and reductions in mean birth weight and
                                                                                            and mutagenicity in                                           risk of small for gestational age. There was no
                                                                                            drinking water.                                               association between preterm delivery and ele-
                                                                                                                                                          vated levels of HAAs, MX, or mutagenicity. A
                                                                                                                                                          reduced risk of preterm delivery was observed
                                                                                                                                                          with high THM exposures. Gestational age
                                                                                                                                                          was associated with exposure to THMs and
                                       Yang et al.      Large cross-sectional             Compared maternal             Low birth weight,               Residence in area supplied with chlorinated
                                         2004 (and        studies in Taiwan,                consumption of                preterm delivery.               drinking water showed a statistically significant
                                         Yang et          1994–1996.                        chlorinated drinking                                          association with preterm delivery. No associa-
                                         al. 2000).                                         water (yes/no).                                               tion was seen between chlorinated drinking
                                                                                                                                                          water and low birth weight.
                                       Fenster et       Small prospective study           Examined TTHM levels          Sperm motility, sperm           No association between TTHM level and sperm
                                         al. 2003.       in California, 1990–               within the 90 days            morphology.                     mobility or morphology. BDCM was inversely
                                                         1991.                              preceding semen col-                                          associated with linearity of sperm motion.
                                                                                            lection.                                                      There was some suggestion that water con-
                                                                                                                                                          sumption and other ingestion metrics may be
                                                                                                                                                          associated with different indicators of semen
                                       Shaw et al.      2 case-control maternal           Estimated THM levels          Neural tube defects, oral       No associations or exposure-response relation
                                         2003.            interview studies: CA,            for mothers’ resi-            clefts, selected heart          were observed between malformations and
                                                          1987–1991.                        dences from before            defects.                        TTHMs in either study.
                                                                                            conception through
                                                                                            early pregnancy.
                                       Windham et       Prospective study: CA,            Estimated exposure to         Menstrual cycle, fol-           Findings suggest that THM exposure may affect
                                        al. 2003.         1990–1991.                        THMs through show-           licular phase length             ovarian function. All brominated THM com-
                                                                                            ering and ingestion          (in days).                       pounds were associated with significantly
                                                                                            over average of 5.6                                           shorter menstrual cycles with the strongest
                                                                                            menstrual cycles per                                          finding for chlorodibromomethane. There was
                                                                                            woman.                                                        little association between TTHM exposure and
                                                                                                                                                          luteal phase length, menses length, or cycle
                                       Wright et al.    Cross-sectional study:            Estimated TTHM expo-      Birth weight, small for             Statistically significant associations between 2nd
                                        2003.             Massachusetts, 1990.              sure in women during      gestational age,                    trimester and pregnancy average TTHM expo-
                                                                                            pregnancy (average        preterm delivery, ges-              sure and small for gestational age and fetal
                                                                                            for pregnancy and         tational age.                       birth weight were detected. Small, statistically
                                                                                            during each trimester).                                       significant increases in gestational duration/
                                                                                                                                                          age were observed at increased TTHM levels,
                                                                                                                                                          but there was little evidence of an association
                                                                                                                                                          between TTHM and preterm delivery or low
                                                                                                                                                          birth weight.
                                       Cedergren      Retrospective case-con-             Examined maternal             Cardiac defects .............   Exposure to chlorine dioxide in drinking water
                                         et al. 2002.   trol study: Sweden,                 periconceptional DBP                                          showed statistical significance for cardiac de-
                                                        1982–1997.                          levels and used GIS                                           fects. THM concentrations of 10 ug/L and
                                                                                            to assign water sup-                                          higher were significantly associated with car-
                                                                                            plies.                                                        diac defects. No excess risk for cardiac defect
                                                                                                                                                          and nitrate were seen.
                                       Hwang et al.     Large cross-sectional             Compared exposure to          Birth defects (neural           Risk of any birth defect, cardiac, respiratory sys-
                                        2002.             study in Norway,                  chlorination (yes/no)         tube defects, cardiac,          tem, and urinary tract defects were signifi-
                                                          1993–1998.                        and water color levels        respiratory system,             cantly associated with water chlorination. Ex-
                                                                                            for mother’s residence        oral cleft, urinary             posure to chlorinated drinking water was sta-
wwhite on PROD1PC65 with RULES2

                                                                                            during pregnancy.             tract).                         tistically significantly associated with risk of
                                                                                                                                                          ventricular septal defects, and an exposure-re-
                                                                                                                                                          sponse pattern was seen. No other specific
                                                                                                                                                          defects were associated with the exposures
                                                                                                                                                          that were examined.

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                                                       TABLE II.D–3.—SUMMARY OF REPRODUCTIVE/DEVELOPMENTAL EPIDEMIOLOGY STUDIES—Continued
                                         Author(s)              Study type                  Exposure(s) studied         Outcome(s) measured                              Findings

                                       Dodds and        Population-based retro-           Estimated THM, chloro-       Neural tube defects,         Exposure to BDCM was associated with in-
                                         King 2001.       spective cohort in                form, and                    cardiovascular de-           creased risk of neural tube defects, cardio-
                                                          Nova Scotia, 1988–                bromodichloromethan-         fects, cleft defects,        vascular anomalies. Chloroform was not asso-
                                                          1995.                             e (BDCM) exposure.           chromosomal abnor-           ciated with neural tube defects, but was asso-
                                                                                                                         malities.                    ciated with chromosomal abnormalities. No as-
                                                                                                                                                      sociation between THM and cleft defects were
                                       Jaakkola et      Large cross-sectional             Compared chlorination        Low birth weight, small      No evidence found for association between pre-
                                         al. 2001.        study in Norway,                  (yes/no) and water           for gestational age,         natal exposure to chlorinated drinking water
                                                          1993–1995.                        color (high/low) for         preterm delivery.            and low birth weight or small for gestational
                                                                                            mother during preg-                                       age. A reduced risk of preterm delivery was
                                                                                            nancy.                                                    noted for exposure to chlorinated water with
                                                                                                                                                      high color content.
                                        ¨ ´
                                       Kallen and       Large cross-sectional             Linked prenatal expo-        Gestational duration,        A statistically significant difference was found for
                                         Robert           cohort study in Swe-              sure to drinking water      birth weight, intra-          short gestational duration and low birth weight
                                         2000.            den, 1985–1994.                   disinfected with var-       uterine growth, mor-          among infants whose mother resided in areas
                                                                                            ious methods (no            tality, congenital mal-       using sodium hypochlorite, but not for chlorine
                                                                                            chlorine, chlorine di-      formations, and other         dioxide. Sodium hypochlorite was also associ-
                                                                                            oxide only, sodium          birth outcomes.               ated with other indices of fetal development
                                                                                            hypochlorite only).                                       but not with congenital defects. No other ef-
                                                                                                                                                      fects were observed for intrauterine growth,
                                                                                                                                                      childhood cancer, infant mortality, low Apgar
                                                                                                                                                      score, neonatal jaundice, or neonatal
                                                                                                                                                      hypothyroidism in relation to either disinfection
                                       Dodds et al.     Population-based retro-           Estimated TTHM level         Low birth weight,            A statistically significant increased risk for still-
                                         1999 (and        spective cohort study             for women during             preterm birth, small         births and high total THMs and specific THMs
                                         King et al.      in Nova Scotia, 1988–             pregnancy.                   for gestational age,         during pregnancy was detected, with higher
                                         2000b).          1995.                                                          stillbirth, chromosomal      risks observed among asphyxia-related still-
                                                                                                                         abnormalities, neural        births. Bromodichloromethane had the strong-
                                                                                                                         tube defects, cleft de-      est association and exhibited an exposure-re-
                                                                                                                         fects, major cardiac         sponse pattern. There was limited evidence of
                                                                                                                         defects.                     an association between THM level and other
                                                                                                                                                      reproductive outcomes. No congenital anoma-
                                                                                                                                                      lies were associated with THM exposure, ex-
                                                                                                                                                      cept for a non-statistically significant associa-
                                                                                                                                                      tion with chromosomal abnormalities.
                                       Klotz and        Population-based case-            Estimated exposure of        Neural tube defects ......   A significant association was seen between ex-
                                         Pyrch            control study in New              pregnant mothers to                                       posure to THMs and neural tube defects. No
                                         1999 (and        Jersey, 1993–1994.                TTHMs and HAAs,                                           associations were observed for neural tube
                                         Klotz and                                          and compared source                                       defects       and      haloacetic     acids     or
                                         Pyrch                                              of water.                                                 haloacetonitriles.
                                       Magnus et        Large cross-sectional             Compared chlorination        Birth defects (neural        Statistically significant associations were seen
                                         al. 1999.        study in Norway,                  (yes/no) and water           tube defects, major          between urinary tract defects and chlorination
                                                          1993–1995.                        color (high/low) at          cardiac, respiratory,        and high water color (high content of organic
                                                                                            mothers’ residences          urinary, oral cleft).        compounds). No associations were detected
                                                                                            at time of birth.                                         for other outcomes or all birth defects com-
                                                                                                                                                      bined. A non-statistically significant, overall ex-
                                                                                                                                                      cess risk of birth defects was seen within mu-
                                                                                                                                                      nicipalities with chlorination and high water
                                                                                                                                                      color compared to municipalities with no
                                                                                                                                                      chlorination and low color.
                                       Gallagher et     Retrospective cohort              Estimated THM levels in      Low birth weight, term       Weak, non-statistically significant association
                                        al. 1998.         study of newborns in              drinking water during        low birthweight, and         with low birth weight and TTHM exposure dur-
                                                          Colorado, 1990–1993.              third trimester of preg-     preterm delivery.            ing the third trimester. Large statistically sig-
                                                                                            nancy.                                                    nificant increase for term low birthweight at
                                                                                                                                                      highest THM exposure levels. No association
                                                                                                                                                      between preterm delivery and THM exposure.
                                       Swan et al.      Prospective study in     Compared consumption                  Spontaneous abortion ...     Pregnant women who drank cold tap water com-
                                        1998.             California, 1990–1991.   of cold tap water to                                               pared to those who consumed no cold tap
                                                                                   bottled water during                                               water showed a significant finding for sponta-
                                                                                   early pregnancy.                                                   neous abortion at one of three sites.
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                                                       TABLE II.D–3.—SUMMARY OF REPRODUCTIVE/DEVELOPMENTAL EPIDEMIOLOGY STUDIES—Continued
                                         Author(s)              Study type                  Exposure(s) studied         Outcome(s) measured                              Findings

                                       Waller et al.    Prospective cohort in    Estimated TTHM levels                 Spontaneous abortion ...     Statistically significant increased risk between
                                        1998 (and         California, 1989–1991.   during first trimester                                             high intake of TTHMs and spontaneous abor-
                                        Waller et                                  of pregnancy via in-                                               tion compared to low intake. BDCM statis-
                                        al. 2001).                                 gestion and show-                                                  tically associated with increased spontaneous
                                                                                   ering.                                                             abortion; other THMs not. Reanalysis of expo-
                                                                                                                                                      sure yielded less exposure misclassification
                                                                                                                                                      and relative risks similar in magnitude to ear-
                                                                                                                                                      lier study. An exposure-response relationship
                                                                                                                                                      was seen between spontaneous abortion and
                                                                                                                                                      ingestion exposure to TTHMs.
                                       Kanitz et al.    Cross-sectional study in          Compared 3 types of          Low birth weight, body       Smaller body length and small cranial circum-
                                         1996.            Italy, 1988–1989.                 water treatment (chlo-       length, cranial circum-      ference showed statistical significant associa-
                                                                                            rine dioxide, sodium         ference, preterm de-         tion with maternal exposure to chlorinated
                                                                                            hypochlorite, and            livery, and other ef-        drinking water. Neonatal jaundice linked statis-
                                                                                            chlorine dioxide/so-         fects.                       tically to prenatal exposure to drinking water
                                                                                            dium hypochlorite).                                       treated with chlorine dioxide. Length of preg-
                                                                                                                                                      nancy, type of delivery, and birthweight
                                                                                                                                                      showed no association.
                                       Bove et al.      Large cohort cross-sec-           Examined maternal ex-        Low birth weight, fetal      Weak, statistically significant increased risk
                                         1995 (and        tional study in New               posure to TTHM and           deaths, small for ges-       found for higher TTHM levels with small for
                                         Bove et          Jersey, 1985–1988.                various other contami-       tational age, birth de-      gestational age, neural tube defects, central
                                         al. 1992a                                          nants.                       fects (neural tube de-       nervous system defects, oral cleft defects, and
                                         & 1992b).                                                                       fects, oral cleft, cen-      major cardiac defects. Some association with
                                                                                                                         tral nervous system,         higher TTHM exposure and low birth weight.
                                                                                                                         major cardiac).              No effect seen for preterm birth, very low birth
                                                                                                                                                      weight, or fetal deaths.
                                       Savitz et al.    Population-based case-            Examined TTHM con-           Spontaneous abortion,        There was a statistically significant increased
                                         1995.            control study: North              centration at resi-          preterm delivery, low        miscarriage risk with high THM concentration,
                                                          Carolina, 1988–1991.              dences and water             birth weight.                but THM intake (based on concentration times
                                                                                            consumption (during                                       consumption level) was not related to preg-
                                                                                            first and third tri-                                      nancy outcome. No associations were seen for
                                                                                            mesters).                                                 preterm delivery or low birth weight. Water
                                                                                                                                                      source was not related to pregnancy outcome
                                                                                                                                                      either, with the exception of a non-significant,
                                                                                                                                                      increased risk of spontaneous abortion for bot-
                                                                                                                                                      tled water users. There was a non-statistically
                                                                                                                                                      significant pattern of reduced risk with in-
                                                                                                                                                      creased consumption of water for all three out-
                                       Aschengrau     Case-control study in               Source of water and 2        Neonatal death, still-       There was a non-significant, increased associa-
                                         et al. 1993.   Massachusetts, 1977–                types of water treat-        birth, congenital            tion between frequency of stillbirths and mater-
                                                        1980.                               ment (chlorination,          anomalies.                   nal     exposure      to    chlorinated   versus
                                                                                            chloramination).                                          chloraminated surface water. An increased risk
                                                                                                                                                      of urinary track and respiratory track defects
                                                                                                                                                      and chlorinated water was detected. Neonatal
                                                                                                                                                      death and other major malformations showed
                                                                                                                                                      no association. No increased risk seen for any
                                                                                                                                                      adverse pregnancy outcomes for surface
                                                                                                                                                      water versus ground and mixed water use.
                                       Kramer et        Population-based case-            Examined chloroform,         Low birth weight, pre-       Statistically significant increased risk for intra-
                                         al. 1992.        control study in Iowa,            DCBM, DBCM, and              maturity, intrauterine       uterine growth retardation effects from chloro-
                                                          1989–1990.                        bromoform levels and         growth retardation.          form exposure were observed. Non-significant
                                                                                            compared type of                                          increased risks were observed for low birth
                                                                                            water source (surface,                                    weight and chloroform and for intrauterine
                                                                                            shallow well, deep                                        growth retardation and DCBM. No intrauterine
                                                                                            well).                                                    growth retardation or low birth weight effects
                                                                                                                                                      were seen for the other THMs, and no effects
                                                                                                                                                      on prematurity were observed for any of the
                                       Shaw et al.      Small case-control                Estimated chlorinated        Congenital cardiac           Following reanalysis, no association between
                                         1991 (and       study: Santa Clara                 tap water consump-           anomalies.                   cardiac anomalies and TTHM level were ob-
                                         Shaw et         County, CA, 1981–                  tion, mean maternal                                       served.
                                         al. 1990).      1983.                              TTHM level, show-
                                                                                            ering/bathing expo-
                                                                                            sure at residence dur-
                                                                                            ing first trimester.
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                                       Aschengrau     Case-control study in               Source of water and ex-      Spontaneous abortion ...     A statistically significantly association was de-
                                         et al. 1989.   Massachusetts, 1976–                posure to metals and                                      tected between surface water source and fre-
                                                        1978.                               other contaminants.                                       quency of spontaneous abortion.

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                                       404               Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                                     TABLE II.D–3.—SUMMARY OF REPRODUCTIVE/DEVELOPMENTAL EPIDEMIOLOGY STUDIES—Continued
                                         Author(s)              Study type                  Exposure(s) studied         Outcome(s) measured                              Findings

                                       Hwang and        Review and meta-anal-             Compared DBP levels,         Birth defects (respiratory   The meta-analysis supports an association be-
                                         Jakkola          ysis of 5 studies.                source of water, chlo-       system, urinary sys-         tween exposure to chlorination by-products
                                         2003.                                              rine residual, color         tem, neural tube de-         and the risk of any birth defect, particularly the
                                                                                            (high/low), and 2            fects, cardiac, oral         risk of neural tube defects and urinary system
                                                                                            types of disinfection:       cleft).                      defects.
                                                                                            chlorination and
                                       Bove et al.      Qualitative review of 14          Examined THM levels.         Birth defects, small for     Review found the studies of THMs and adverse
                                         2002.           studies.                           Compared drinking            gestational age, low         birth outcomes provide moderate evidence for
                                                                                            water source and type        birth weight, preterm        associations with small for gestational age,
                                                                                            of water treatment.          delivery, spontaneous        neural tube defects, and spontaneous abor-
                                                                                                                         abortion, fetal death.       tions. Authors felt risks may have been under-
                                                                                                                                                      estimated and exposure-response relation-
                                                                                                                                                      ships       distorted    due    to      exposure
                                       Graves et al.    Review of toxicological           Examined water con-          Low birth weight,            Weight of evidence suggested positive associa-
                                         2001.            and epidemiological               sumption, duration of        preterm delivery,            tion with DBP exposure for growth retardation
                                                          studies using a weight            exposure, THM levels,        small for gestational        such as small for gestational age or intra-
                                                          of evidence approach.             HAA levels, and other        age, intrauterine            uterine growth retardation and urinary tract de-
                                                                                            contaminants. Com-           growth retardation,          fects. Review found no support for DBP expo-
                                                                                            pared source of              specific birth defects,      sure and low birth weight, preterm delivery,
                                                                                            water, water treat-          neonatal death, de-          some specific birth defects, and neonatal
                                                                                            ment, water color            creased fertility, fetal     death, and inconsistent findings for all birth de-
                                                                                            (high/low), etc.             resorption, and other        fects, all central nervous system defects, neu-
                                                                                                                         effects.                     ral tube defects, spontaneous abortion, and
                                       Villanueva et    Qualitative review of 14          Compared exposure to         Spontaneous abortion,        Review found positive associations between in-
                                          al. 2001.      reproductive and de-               TTHM levels, muta-           low birth weight, small      creased spontaneous abortion, low birth
                                                         velopmental health ef-             genic drinking water,        for gestational age,         weight, small for gestational age, and neural
                                                         fect studies.                      water consumption,           neural tube defects,         tube defects and drinking chlorinated water in
                                                                                            source water, types of       other reproductive           most studies, although not always with statis-
                                                                                            disinfection                 and developmental            tical significance.
                                                                                            (chlorination and            outcomes.
                                                                                            chloramination), and
                                                                                            residence times.
                                       Nieuwenhuij-     Qualitative review of nu-         Examined levels of var-      Low birth weight,            The review supports some evidence of associa-
                                         sen et al.      merous toxicological               ious DBPs, water con-        preterm delivery,            tion between THMs and low birth weight, but
                                         2000.           and epidemiological                sumption, and dura-          spontaneous abor-            inconclusive. Review found no evidence of as-
                                                         studies.                           tion of exposure.            tions, stillbirth, birth     sociation between THMs and preterm delivery,
                                                                                            Compared water               defects, etc.                and that associations for other outcomes
                                                                                            color, water treatment,                                   (spontaneous abortions, stillbirth, and birth de-
                                                                                            source of water, etc.                                     fects) were weak but gaining weight.
                                       Reif et al.      Qualitative reviews of            Compared source of           Birth weight, low birth      Weight of evidence suggested DBPs are repro-
                                         2000.           numerous epidemio-                 water supply and             weight, intrauterine         ductive toxicants in humans under appropriate
                                                         logical studies.                   methods of disinfec-         growth retardation,          exposure conditions. The review reports find-
                                                                                            tion. Estimated TTHM         small for gestational        ings between TTHMs and effects on fetal
                                                                                            levels.                      age, preterm deliver,        growth, fetal viability, and congenital anoma-
                                                                                                                         somatic parameters,          lies as inconsistent. Reviewers felt data are at
                                                                                                                         neonatal jaundice,           the stage of hazard identification and did not
                                                                                                                         spontaneous abortion,        suggest a dose-response pattern of increasing
                                                                                                                         stillbirth, develop-         risk with increasing TTHM concentration.
                                                                                                                         mental anomalies.
                                       WHO 2000         Qualitative reviews of            Various exposures to         Various reproductive         Review found some support for an association
                                                         various studies in Fin-            THMs.                        and developmental ef-        between increased risks of neural tube defects
                                                         land, U.S., and Can-                                            fects.                       and miscarriage and THM exposure. Other as-
                                                         ada.                                                                                         sociations have been observed, but the au-
                                                                                                                                                      thors believed insufficient data exist to assess
                                                                                                                                                      any of these associations.
                                       Craun, ed.       Qualitative review of 10          Examined THM levels          Stillbirth, neonatal         Associations between DBPs and various repro-
                                         1998.           studies, focus on Cali-            and water consump-           death, spontaneous           ductive effects were seen in some epidemio-
                                                         fornia cohort study.               tion, and compared           abortion, low birth          logical studies, but the authors felt these re-
                                                                                            source of water and          weight, preterm deliv-       sults do not provide convincing evidence for a
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                                                                                            water treatment (chlo-       ery, intrauterine            causal relationship between DBPs and repro-
                                                                                            rine, chloramines,           growth retardation,          ductive effects.
                                                                                            chlorine dioxide).           neonatal jaundice,
                                                                                                                         birth defects.

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                                                      TABLE II.D–3.—SUMMARY OF REPRODUCTIVE/DEVELOPMENTAL EPIDEMIOLOGY STUDIES—Continued
                                         Author(s)              Study type                  Exposure(s) studied         Outcome(s) measured                              Findings

                                       Mills et al.     Qualitative review of 22          Examined TTHM levels         Various reproductive          Review found studies suggest possible increases
                                         1998.           studies.                           and water consump-           and developmental ef-         in adverse reproductive and developmental ef-
                                                                                            tion. Compared               fects.                        fects, such as increased spontaneous abortion
                                                                                            source of water and 2                                      rates, small for gestational age, and fetal
                                                                                            types of water treat-                                      anomalies, but that insufficient evidence exists
                                                                                            ment (chlorination and                                     to establish a causal relationship.
                                       Reif et al.      Review of 3 case-con-             Examined THM levels at       Birth defects (central        Studies reviewed suggest that exposure to DBPs
                                         1996.            trol studies and 1                residences, dose con-        nervous system, neu-          may increase intrauterine growth retardation,
                                                          cross-sectional study.            sumption, chloroform.        ral tube defects, car-        neural tube defects, major heart defects, and
                                                                                            Compared source of           diac, oral cleft, res-        oral cleft defects. Review found epidemiologic
                                                                                            waters and 2 types of        piratory, urinary tract),     evidence supporting associations between ex-
                                                                                            water treatment              spontaneous abortion,         posure to DBPs and adverse pregnancy out-
                                                                                            (chlorination and            low birth weight,             comes to be sparse and to provide an inad-
                                                                                            chloramination).             growth retardation,           equate basis to identify DBPs as a reproduc-
                                                                                                                         preterm delivery,             tive or developmental hazard.
                                                                                                                         intrauterine growth re-
                                                                                                                         tardation, stillbirth,
                                                                                                                         neonatal death.
                                       Swan et al.      Qualitative review of 5           Compared maternal            Spontaneous abortion ...      Four of the studies reviewed suggest that
                                        1992.            studies in Santa Clara             consumption of resi-                                       women drinking bottled water during the first
                                                         County, CA (Deane et               dence tap water to                                         trimester of pregnancy may have reduced risk
                                                         al. 1992, Wrensch et               bottled water.                                             of spontaneous abortion relative to drinking
                                                         al. 1992, Hertz-                                                                              tap water. No association seen in the fifth
                                                         Picciotto et al. 1992,                                                                        study. Review concluded that if findings are
                                                         Windham et al. 1992,                                                                          causal and not due to chance or bias, data
                                                         Fenster et al. 1992).                                                                         suggest a 10–50% increase in spontaneous
                                                                                                                                                       abortion risk for pregnant women drinking tap
                                                                                                                                                       water over bottled water.

                                         ii. Toxicology. To date, the majority of               endpoints. The authors identified a                    possible association between adverse
                                       reproductive and developmental                           NOAEL and LOAEL of 50 ppm and 150                      reproductive and developmental health
                                       toxicology studies have been short term                  ppm, respectively, based on delayed                    effects and exposure to chlorinated
                                       and higher dose. Many of these studies                   sexual maturation for BDCM and a                       surface water.
                                       are summarized in a review by Tyl                        NOAEL and LOAEL of 50 ppm and 250                         c. Conclusions. EPA’s weight of
                                       (2000). A summary of this review and of                  ppm based on abnormal                                  evidence evaluation of the best available
                                       additional studies is provided in the                    spermatogenesis for DBAA. The authors                  science on carcinogenicity and
                                       proposed Stage 2 DBPR (USEPA 2003a).                     concluded that similar effects in                      reproductive and developmental effects,
                                       Individual DBP supporting documents                      humans would only be seen at levels                    in conjunction with the widespread
                                       evaluate and assess additional studies as                many orders of magnitude higher than                   exposure to DBPs, supports the
                                       well (USEPA 2000b; USEPA 2000c;                          that of current drinking water levels. As              incremental regulatory changes in
                                       USEPA 2001a; USEPA 2001b; USEPA                          discussed in more detail in the                        today’s rule that target lowering DBPs
                                       2003b; USEPA 2005b; USEPA 2005c;                         proposal, EPA believes that because of                 and providing equitable public health
                                       USEPA 2005d; USEPA 2005e; USEPA                          key methodological differences                         protection.
                                       2005k). A number of recent studies have                  indicated as being important in other                     EPA believes that the cancer
                                       been published that include in vivo and                  studies (Bielmeier et al. 2001; Bielmeier              epidemiology and toxicology literature
                                       in vitro assays to address mechanism of                  et al. 2004; Kaydos et al. 2004;                       provide important information that
                                       action. Overall, reproductive and                        Klinefelter et al. 2001; Klinefelter et al.            contributes to the weight of evidence for
                                       developmental toxicology studies                         2004), definitive conclusions regarding                potential health risks from exposure to
                                       indicate a possible reproductive/                        BDCM and DBAA cannot be drawn.                         chlorinated drinking water. At this time,
                                       developmental health hazard although                     Other multi-generation research                        the cancer epidemiology studies support
                                       they are preliminary in nature for the                   underway includes a study on BCAA,                     a potential association between
                                       majority of DBPs, and the dose-response                  but this research is not yet published.                exposure to chlorinated drinking water
                                       characteristics of most DBPs have not                       Biological plausibility for the effects             and cancer, but evidence is insufficient
                                       been quantified. Some of the                             observed in reproductive and                           to establish a causal relationship. The
                                       reproductive effects of DCAA were                        developmental epidemiological studies                  epidemiological evidence for an
                                       quantified as part of the RfD                            has been demonstrated through various                  association between DBP exposure and
                                       development process, and impacts of                      toxicological studies on some individual               colon and rectal cancers is not as
                                       DCAA on testicular structure are one of                  DBPs (e.g., Bielmeier et al. 2001;                     consistent as it is for bladder cancer,
                                       the critical effects in the study that is                Bielmeier et al. 2004; Narotsky et al.                 although similarity of effects reported in
                                       the basis of the RfD (USEPA 2003b).                      1992; Chen et al. 2003; Chen et al.                    animal toxicity and human
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                                         A few long term, lower dose studies                    2004). Some of these studies were                      epidemiology studies strengthens the
                                       have been completed. Christian et al.                    conducted at high doses, but similarity                evidence for an association with colon
                                       (2002a and 2002b) looked for an                          of effects observed between toxicology                 and rectal cancers. EPA believes that the
                                       association between BDCM and DBAA                        studies and epidemiology studies                       overall cancer epidemiology and
                                       and reproductive and developmental                       strengthens the weight of evidence for a               toxicology data support the decision to

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                                       pursue additional DBP control measures                  the ICR was supplemented by a survey                   addressing high DBP concentrations that
                                       as reflected in the Stage 2 DBPR.                       conducted by the National Rural Water                  occur at particular locations or in single
                                          Based on the weight of evidence                      Association, data provided by various                  samples within systems in compliance.
                                       evaluation of the reproductive and                      States, the Water Utility Database
                                       developmental epidemiology data, EPA                                                                           2. Treatment
                                                                                               (which contains data collected by the
                                       concludes that a causal link between                    American Water Works Association),                        The analysis of the new treatment
                                       adverse reproductive or developmental                   and ICR Supplemental Surveys for small                 study data confirmed that certain
                                       health effects and exposure to                          and medium water systems.                              technologies are effective at reducing
                                       chlorinated drinking water or DBPs has                     After analyzing the DBP occurrence                  DBP concentrations. Bench- and pilot-
                                       not been established, but that there is a               data, EPA and the Advisory Committee                   scale studies for granular activated
                                       potential association. Despite                          reached three significant conclusions                  carbon (GAC) and membrane
                                       inconsistent findings across studies,                   that in part led the Advisory Committee                technologies required by the
                                       some recent studies continue to suggest                 to recommend further control of DBPs                   Information Collection Rule provided
                                       associations between DBP exposure and                   in public water systems. First, the data               information on the effectiveness of the
                                       various adverse reproductive and                        from the Information Collection Rule                   two technologies. Other studies found
                                       developmental effects. In addition, data                showed that the RAA compliance                         UV light to be highly effective for
                                       from a number of toxicology studies,                    calculation under the Stage 1 DBPR                     inactivating Cryptosporidium and
                                       although the majority of them were                      allows elevated TTHM or HAA5 levels                    Giardia at low doses without promoting
                                       conducted using high doses,                             to regularly occur at some locations in                the formation of DBPs (Malley et al.
                                       demonstrate biological plausibility for                 the distribution system while the overall              1996; Zheng et al. 1999). This new
                                       some of the effects observed in                         average of TTHM or HAA5 levels at all                  treatment information adds to the
                                       epidemiology studies. EPA concludes                     DBP monitoring locations is below the                  treatment options available to utilities
                                       that no dose-response relationship or                   MCLs of the Stage 1 DBPR. Customers                    for controlling DBPs beyond the
                                       causal link has been established                        served at those sampling locations with                requirements of the Stage 1 DBPR.
                                       between exposure to chlorinated                         DBP levels that are regularly above
                                       drinking water or disinfection                          0.080 mg/L TTHM and 0.060 mg/L                         E. Conclusions for Regulatory Action
                                       byproducts and adverse developmental                    HAA5 experience higher exposure                           After extensive analysis of available
                                       or reproductive health effects. EPA’s                   compared to customers served at                        data and rule options considered by the
                                       evaluation of the best available studies,               locations where these levels are                       Advisory Committee and review of
                                       particularly epidemiology studies is that               consistently met.                                      public comments on the proposed Stage
                                       they do not support a conclusion at this                   Second, the new data demonstrated                   2 DBPR (USEPA, 2003a), EPA is
                                       time as to whether exposure to                          that DBP levels in single samples can be               finalizing a Stage 2 DBPR control
                                       chlorinated drinking water or                           substantially above 0.080 mg/L TTHM                    strategy consistent with the key
                                       disinfection byproducts causes adverse                  and 0.060 mg/L HAA5. Some customers                    elements of the Agreement in Principle
                                       developmental and reproductive health                   receive drinking water with                            signed in September 2000 by the
                                       effects, but do provide an indication of                concentrations of TTHM and HAA5 up                     participants in the Stage 2 M–DBP
                                       a potential health concern that warrants                to 75% above 0.080 mg/L and 0.060 mg/                  Advisory Committee. EPA believes that
                                       incremental regulatory action beyond                    L, respectively, even when their water                 exposure to chlorinated drinking water
                                       the Stage 1 DBPR.                                       system is in compliance with the Stage                 may be associated with cancer,
                                                                                               1 DBPR. Some studies support an                        reproductive, and developmental health
                                       D. DBP Occurrence and DBP Control                       association between acute exposure to                  risks. EPA determined that the risk-
                                          New information on the occurrence of                 DBPs and potential adverse                             targeting measures recommended in the
                                       DBPs in distribution systems raises                     reproductive and developmental health                  Agreement in Principle will require
                                       issues about the protection provided by                 effects (see Section III.C for more detail).           only those systems with the greatest risk
                                       the Stage 1 DBPR. This section presents                    Third, the data from the Information                to make treatment and operational
                                       new occurrence and treatment                            Collection Rule revealed that the highest
                                                                                                                                                      changes and will maintain simultaneous
                                       information used to identify key issues                 TTHM and HAA5 levels can occur at
                                                                                                                                                      protection from potential health
                                       and to support the development of the                   any monitoring site in the distribution
                                                                                                                                                      concerns from DBPs and microbial
                                       Stage 2 DBPR. For a more detailed                       system. In fact, the highest
                                                                                                                                                      contaminants. EPA has carefully
                                       discussion see the proposed Stage 2                     concentrations did not occur at the
                                                                                                                                                      evaluated and expanded upon the
                                       DBPR (USEPA 2003a). For additional                      maximum residence time locations in
                                                                                                                                                      recommendations of the Advisory
                                       information on occurrence of regulated                  more than 50% of all ICR samples. The
                                                                                                                                                      Committee and public comments to
                                       and nonregulated DBPs, see the                          fact that the locations with the highest
                                                                                                                                                      develop today’s rule. EPA also made
                                       Occurrence Assessment for the Final                     DBP levels vary in different public
                                                                                                                                                      simplifications where possible to
                                       Stage 2 Disinfectants and Disinfection                  water systems indicates that the Stage 1
                                                                                                                                                      minimize complications for public
                                       Byproducts Rule (USEPA 2005f).                          DBPR monitoring may not accurately
                                                                                                                                                      water systems as they transition to
                                                                                               represent the high DBP concentrations
                                       1. Occurrence                                                                                                  compliance with the Stage 2 DBPR
                                                                                               that actually exist in distribution
                                          EPA, along with the M-DBP Advisory                                                                          while expanding public health
                                                                                               systems, and that additional monitoring
                                       Committee, collected, developed, and                                                                           protection. The requirements of the
                                                                                               is needed to identify distribution system
                                       evaluated new information that became                                                                          Stage 2 DBPR are described in detail in
                                                                                               locations with elevated DBP levels.
                                       available after the Stage 1 DBPR was                       These data showed that efforts beyond               Section IV of this preamble.
                                       published. The Information Collection                   the Stage 1 DBPR are needed to provide                 IV. Explanation of Today’s Action
                                       Rule (ICR) (USEPA 1996) provided new                    more equitable protection from DBP
                                                                                                                                                      A. MCLGs
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                                       field data on DBP exposure for large                    exposure across the entire distribution
                                       water systems and new study data on                     system. The incremental regulatory                        MCLGs are set at concentration levels
                                       the effectiveness of several DBP control                changes made under the Stage 2 DBPR                    at which no known or anticipated
                                       technologies. The unprecedented                         meet this need by reevaluating the                     adverse health effects occur, allowing
                                       amount of information collected under                   locations of DBP monitoring sites and                  for an adequate margin of safety.

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                                       Establishment of an MCLG for each                       1. Chloroform MCLG                                     of 0.01 mg/kg/day and an adult tap
                                       specific contaminant is based on the                       a. Today’s rule. The final MCLG for                 water consumption of 2 L per day for a
                                       available evidence of carcinogenicity or                chloroform is 0.07 mg/L. The MCLG was                  70 kg adult. A relative source
                                       noncancer adverse health effects from                   calculated using toxicological evidence                contribution (RSC) of 20% was used in
                                       drinking water exposure using EPA’s                     that the carcinogenic effects of                       accordance with Office of Water’s
                                       guidelines for risk assessment. MCLGs                   chloroform are due to sustained tissue                 current approach for deriving RSC
                                       are developed to ensure they are                        toxicity. EPA is not changing the other                through consideration of data that
                                       protective of the entire population.                    THM MCLGs finalized in the Stage 1                     indicate that other routes and sources of
                                          Today’s rule provides MCLGs for                      DBPR.                                                  exposure may potentially contribute
                                                                                                  b. Background and analysis. The                     substantially to the overall exposure to
                                       chloroform and two haloacetic acids,
                                                                                               MCLG for chloroform is unchanged                       chloroform. See the proposed Stage 2
                                       monochloroacetic acid (MCAA) and
                                                                                               from the proposal. The MCLG is                         DBPR (USEPA 2003a) for a detailed
                                       trichloroacetic acid (TCAA).
                                                                                               calculated using a reference dose (RfD)                discussion of the chloroform MCLG.

                                                                                                        (0.01 mg/kg /day)(70 kg)(0.2)
                                                                      MCLG for Chloroform =                                           = 0.07 mg/L (rounded)
                                                                                                                  2 L/day

                                          Based on an analysis of the available                carcinogenic to humans under                           MCLGs for TCAA and MCAA of 0.02
                                       scientific data on chloroform, EPA                      conditions that do not cause                           mg/L and 0.03 mg/L, respectively, in the
                                       believes that the chloroform dose-                      cytotoxicity and cell regeneration                     Stage 2 proposal (USEPA 2003a). The
                                       response is nonlinear and that                          (USEPA 2001a). Therefore, the dose-                    proposed TCAA MCLG and its
                                       chloroform is likely to be carcinogenic                 response is nonlinear, and the MCLG is                 supporting analysis is being finalized
                                       only under high exposure conditions                     set at 0.07 mg/L. This conclusion has                  unchanged in today’s final rule. The
                                       (USEPA 2001a). This assessment is                       been reviewed by the SAB (USEPA                        MCLG calculation for MCAA is revised
                                       supported by the principles of the 1999                 2000d), who agree that nonlinear                       in this final rule, based on a new
                                       EPA Proposed Guidelines for                             approach is most appropriate for the                   reference dose, as discussed later. See
                                       Carcinogen Risk Assessment (USEPA                       risk assessment of chloroform; it also                 the proposed Stage 2 DBPR (USEPA
                                       1999a) and reconfirmed by the 2005                      remains consistent with the principles                 2003a) for a detailed discussion of the
                                       final Cancer Guidelines (USEPA 2005i).                  of the 1999 EPA Proposed Guidelines                    calculation of the MCLGs.
                                       The science in support of a nonlinear                   for Carcinogenic Risk Assessment
                                       approach for estimating the                                                                                       TCAA. The MCLG for TCAA was
                                                                                               (USEPA 1999a) and the final Cancer                     calculated based on the RfD of 0.03 mg/
                                       carcinogenicity of chloroform was                       Guidelines ( USEPA 2005i), which
                                       affirmed by the Chloroform Risk                                                                                kg/day using a 70 kg adult body weight,
                                                                                               allow for nonlinear extrapolation.
                                       Assessment Review Subcommittee of                                                                              a 2 L/day drinking water intake, and a
                                                                                                  EPA also received some comments
                                       the EPA SAB Executive Committee                         requesting a combined MCLG for THMs                    relative source contribution of 20%. An
                                       (USEPA 2000d). Since the nonzero                        or HAAs. This is not appropriate                       additional tenfold risk management
                                       MCLG is based on a mode of action                       because these different chemicals have                 factor has been applied to account for
                                       consideration specific to chloroform, it                different health effects.                              the possible carcinogenicity of TCAA.
                                       does not affect the MCLGs of other                                                                             This approach is consistent with EPA
                                       trihalomethanes.                                        2. HAA MCLGs: TCAA and MCAA                            policy. TCAA induces liver tumors in
                                          c. Summary of major comments. EPA                       a. Today’s rule. Today’s rule finalizes             mice (Ferreira-Gonzalez et al. 1995;
                                       received many comments in support of                    the proposed Stage 2 MCLG for TCAA                     Pereira 1996; Pereira and Phelps 1996;
                                       the proposed MCLG calculation for                       of 0.02 mg/L (USEPA 2003a) and sets an                 Tao et al. 1996; Latendresse and Pereira
                                       chloroform, although some commenters                    MCLG for MCAA of 0.07 mg/L. EPA is                     1997; Pereira et al. 1997) but not in rats
                                       disagreed with a non-zero MCLG.                         not changing the other HAA MCLGs                       (DeAngelo et al. 1997). Much of the
                                          At this time, based on an analysis of                finalized in the Stage 1 DBPR (USEPA                   recent data on the carcinogenicity of
                                       all the available scientific data on                    1998a).                                                TCAA have focused on examining the
                                       chloroform, EPA concludes that                             b. Background and analysis. The Stage               carcinogenic mode(s) of action.
                                       chloroform is likely to be carcinogenic                 1 DBPR included an MCLG for TCAA of                    However, at this time, neither the
                                       to humans only under high exposure                      0.03 mg/L and did not include an MCLG                  bioassay nor the mechanistic data are
                                       conditions that lead to cytotoxicity and                for MCAA (USEPA 1998a). Based on                       sufficient to support the development of
                                       regenerative hyperplasia and that                       toxicological data published after the                 a slope factor from which to quantify
                                       chloroform is not likely to be                          Stage 1 DBPR, EPA proposed new                         the cancer risk.

                                                                                                     (0.03 mg/kg/day)(70 kg)(0.2)
                                                                             MCLG for TCAA =                                      = 0.02 mg/L (rounded)
                                                                                                            (2 L/day)(10)

                                         The chronic bioassay for TCAA by                      and NOAEL were determined. The data                    NOAEL of 32.5 mg/kg/day for liver
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                                       DeAngelo et al. (1997) was selected as                  are consistent with the findings in both               histopathological changes in rats
                                       the critical study for the development of               the Pereira (1996) chronic drinking                    (DeAngelo et al. 1997). A composite
                                       the RfD. In this chronic drinking water                 water study and the Mather et al. (1990)               uncertainty factor of 1000 was applied
                                       study, a dose-response was noted for                    subchronic drinking water study. The                   in the RfD determination. A default

                                       several endpoints and both a LOAEL                      RfD of 0.03 mg/kg/day is based on the                  uncertainty factor of 10 was applied to

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                                       the RfD to account for extrapolation                    suggesting some presence in the                        change as a NOAEL. Increased spleen
                                       from an animal study because data to                    atmosphere (Reimann et al. 1996);                      weights in the absence of
                                       quantify rat-to-human differences in                    however, due to the low volatility (0.5—               histopathological effects are not
                                       toxicokinetics or toxicodynamics are not                0.7 mm Hg at 25 °C) of TCAA, exposure                  necessarily adverse. In addition, spleen
                                       available. The default uncertainty factor               from ambient air is expected to be                     weights were decreased, rather than
                                       of 10 was used to account for human                     minimal. Dermal exposure to                            increased in the mid- and high-dose
                                       variability in the absence of data on                   disinfected water is also unlikely to be               groups in the DeAngelo et al. (1997)
                                       differences in human susceptibility.                    significant. A study by Xu et al. (2002)               study and were accompanied by a
                                       Although subchronic and chronic                         reports that dermal exposure from                      significant decrease in body weight,
                                       studies of TCAA have been reported for                  bathing and showering is only 0.01% of                 decreased relative and absolute liver
                                       multiple species, many studies have                     that from oral exposure. In addition, the              weights, decreased absolute kidney
                                       focused on liver lesions and a full                     solvents trichloroethylene,                            weight, and an increase in relative testes
                                       evaluation of a wide range of potential                 tetrachlorethylene, 1,1,1-trichloroethane              weight. Accordingly, the mid-dose in
                                       target organs has not been conducted in                 (often found in ambient air and drinking               this same study (26.1 mg/kg/day) has
                                       two different species. In addition, there               water), and the disinfection byproduct                 been categorized as the LOAEL with the
                                       has been no multi-generation study of                   chloral hydrate all contribute to the                  lower 3.5 mg/kg/day dose as a NOAEL.
                                       reproductive toxicity and the data from                 body’s TCAA load since each of these                     Based on a NOAEL of 3.5 mg/kg/day
                                       teratology studies in rats provide                      compounds is metabolized to TCAA                       (DeAngelo et al. 1997), the revised RfD
                                       LOAEL values but no NOAEL for                           (ATSDR 2004; ATSDR 1997a; ATSDR                        was calculated as shown below, with a
                                       developmental toxicity. Thus, an                        1997b; USEPA 2000e). Due to the                        composite uncertainty factor of 300.
                                       additional uncertainty factor of 10 was                 limitations primarily in the dietary data              EPA used a default uncertainty factor of
                                       used to account for database                            and a clear indication of exposure from                10 to account for extrapolation from an
                                       insufficiencies.                                        other sources, EPA applied a relative                  animal study, since no data on rat-to-
                                          The MCLG calculation also includes a                 source contribution of 20%.                            human differences in toxicokinetics or
                                       relative source contribution (RSC) of                      MCAA. The MCLG for MCAA uses                        toxicodynamics were identified. A
                                       20%. The RSC was derived consistent                     the following calculations: An RfD of                  default uncertainty factor of 10 was
                                       with Office of Water’s current approach                 0.01 mg/kg/day, a 70 kg adult                          used to account for human variability in
                                       for deriving RSC. In addition to                        consuming 2 L/day of tap water, and a                  the absence of data on the variability in
                                       disinfected water, foods are expected to                relative source contribution of 20%.                   the toxicokinetics of MCAA in humans
                                       contribute to daily exposure to TCAA                       The RfD included in the proposal was                or in human susceptibility to MCAA.
                                       (Raymer et al. 2001, 2004; Reimann et                   based on a chronic drinking water study                An additional uncertainty factor of three
                                       al. 1996). Some of the TCAA in foods                    in rats conducted by DeAngelo et al.                   was used to account for database
                                       comes from cleaning and cooking foods                   (1997). In the assessment presented for                insufficiencies. Although there is no
                                       in chlorinated water. Additional TCAA                   the proposed rule, the LOAEL from this                 multi-generation reproduction study,
                                       is found in some foods because of the                   study was identified as 3.5 mg/kg/day                  the available studies of reproductive
                                       widespread use of chlorine as a                         based on increased absolute and relative               and developmental processes suggest
                                       sanitizing agent in the food industry                   spleen weight in the absence of                        that developmental toxicity is unlikely
                                       (USFDA 1994). EPA was not able to                       histopathologic changes. After                         to be the most sensitive endpoint. This
                                       identify any dietary surveys or duplicate               reviewing comments and further                         led to the following calculation of the
                                       diet studies of TCAA in the diet. TCAA                  analysis of the data, EPA concludes that               Reference Dose (RfD) and MCLG for
                                       also has been identified in rain water,                 it is more appropriate to identify this                MCAA:

                                                                                     (3.5 mg /kg/day)
                                                                             RfD =                    = 0.012 mg /kg/day rounded to 0.01 mg /kg/day

                                       Where:                                                      exposed to MCA for 104 weeks in                            extrapolation, inter-individual
                                                                                                   drinking water (DeAngelo et al.                            variability in humans, and
                                       3.5 mg/kg/day = NOAEL for decreased
                                                                                                   1997).                                                     deficiencies in the database.
                                           body weight plus decreased liver,                   300 = composite uncertainty factor
                                           kidney and spleen weights in rats                       chosen to account for inter species

                                                                                                           (0.01 mg/kg/day)(70 kg)(0.2)
                                                                                 MCLG for MCAA =                                        = 0.07 mg/L
                                                                                                                     2 L/day

                                          The RSC for MCAA was selected                        did not increase the MCAA content of                   (USFDA 1994). As with TCAA,
                                       using comparable data to that discussed                 foods to the same extent as was                        inhalation and dermal exposures are
                                       for TCAA. MCAA, like TCAA, has been                     observed for TCAA (Raymer et al. 2004).                unlikely to be significant. Dermal
                                       found in foods and is taken up by foods                 MCAA was found to be completely                        exposure from bathing and showering
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                                       during cooking (15% in chicken to 62%                   stable in water boiled for 60 minutes                  was estimated to contribute only 0.03%
                                       in pinto beans) and cleaning (2.5% for                  and is likely to be found in the diet due              of that from oral exposure (Xu et al.
                                       lettuce) with water containing 500 ppb                  to the use of chlorinated water in food                2002). As with TCAA, due to the
                                       MCAA (Reimann et al.1996; Raymer et                     preparation and the use of chlorine as                 limitations in dietary data and a clear

                                       al. 2001, 2004). Rinsing of cooked foods                a sanitizing agent by the food industry                indication of exposure from other

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                                       sources, EPA applied a relative source                  1. Today’s Rule                                        pumping, treatment, equipment, and
                                       contribution of 20%.                                       As public water systems, consecutive                personnel; assuring an adequate supply
                                          c. Summary of major comments. EPA                    systems must provide water that meets                  during peak demand periods; acquiring
                                       received few comments on MCAA and                       the MCLs for TTHM and HAA5 under                       emergency supplies; selling surplus
                                       TCAA. The majority of comments about                    the Stage 2 DBPR, use specified                        supplies; and delivering a better product
                                       the MCLGs for TCAA and MCAA were                        analytical methods, and carry out                      to consumers. EPA estimates that there
                                       general MCLG questions, including RSC                   associated monitoring, reporting,                      are more than 10,000 consecutive
                                       derivation. Some commenters                             recordkeeping, public notification, and                systems nationally.
                                       questioned why MCAA, TCAA, and                          other requirements. The following                        Consecutive systems face particular
                                       chloroform were calculated using an                     discusses a series of definitions needed               challenges in providing water that meets
                                       RSC of 20%. In particular, some                         for addressing consecutive system                      regulatory standards for contaminants
                                       commenters compared these                               requirements in today’s rule. Later                    that can increase in the distribution
                                       calculations to that for DBCM in the                    sections of this preamble provide                      system. Examples of such contaminants
                                       Stage 1 DBPR, which uses 80%. Each of                   further details on how rule requirements               include coliforms, which can grow if
                                       the MCLGs set for chloroform, TCAA,                     (e.g., schedule and monitoring) apply to               favorable conditions exist, and some
                                       and MCAA under this rule is calculated                  consecutive systems.                                   DBPs, including THMs and HAAs,
                                       using the best available science and EPA                   A consecutive system is a public                    which can increase when a disinfectant
                                       Office of Water’s current approach for                  water system that receives some or all                 and DBP precursors continue to react in
                                       deriving the RSC. EPA chose an RSC of                   of its finished water from one or more                 the distribution system.
                                       20%, not 80%, because of clear                          wholesale systems.                                       EPA included requirements
                                       indications of exposure from other                         Finished water is water that has been
                                                                                                                                                      specifically for consecutive systems
                                       sources; data limitations preclude the                  introduced into the distribution system
                                                                                                                                                      because States have taken widely
                                       derivation of a specific RSC.                           of a public water system and is intended
                                                                                                                                                      varying approaches to regulating DBPs
                                                                                               for distribution and consumption
                                          The RSC for DBCM was 80% in the                                                                             in consecutive systems in previous
                                                                                               without further treatment, except as
                                       Stage 1 DBPR. The DBCM MCLG is not                                                                             rules. For example, some States have
                                                                                               necessary to maintain water quality in
                                       part of today’s rulemaking. Any possible                                                                       not regulated DBP levels in consecutive
                                                                                               the distribution system (e.g., booster
                                       future revision to the DBCM MCLG as                                                                            systems that deliver disinfected water
                                                                                               disinfection, addition of corrosion
                                       a result of an RSC change would not                                                                            but do not add a disinfectant. Other
                                                                                               control chemicals).
                                       affect the MCL for TTHM finalized in                                                                           States have determined compliance
                                                                                                  A wholesale system is a public water
                                       today’s rule.                                                                                                  with DBP standards based on the
                                                                                               system that treats source water as
                                                                                                                                                      combined distribution system that
                                          In response to comments received on                  necessary to produce finished water and
                                                                                                                                                      includes both the wholesaler and
                                       the RfD for MCAA, EPA has reviewed                      then delivers finished water to another
                                                                                                                                                      consecutive systems. In this case, sites
                                       the critical study regarding the                        public water system. Delivery may be
                                                                                                                                                      in consecutive systems are treated as
                                       appropriateness of an increase in spleen                through a direct connection or through
                                                                                                                                                      monitoring sites within the combined
                                       weight in the absence of histopathology                 the distribution system of one or more
                                                                                                                                                      distribution system. Neither of these
                                       as a LOAEL. EPA has determined that                     consecutive systems.
                                                                                                  The combined distribution system is                 approaches provide the same level of
                                       the dose associated with this endpoint                                                                         public health protection as non-
                                       is more appropriately categorized as a                  defined as the interconnected
                                                                                               distribution system consisting of the                  consecutive systems receive under the
                                       NOAEL rather than a LOAEL and has                                                                              Stage 1 DBPR. Once fully implemented,
                                       revised the RfD and MCLG for MCAA.                      distribution systems of wholesale
                                                                                               systems and of the consecutive systems                 today’s rule will ensure similar
                                       B. Consecutive Systems                                  that receive finished water from those                 protection for consumers in consecutive
                                                                                               wholesale system(s).                                   systems.
                                         Today’s rule includes provisions for                     EPA is allowing States some                           In developing its recommendations,
                                       consecutive systems, which are public                   flexibility in defining what systems are               the Stage 2 M-DBP Advisory Committee
                                       water systems that receive some or all                  a part of a combined distribution                      recognized two principles related to
                                       of their finished water from another                    system. This provision determines                      consecutive systems: (1) consumers in
                                       water system (a wholesale system).                      effective dates for requirements in                    consecutive systems should be just as
                                       Consecutive systems face particular                     today’s rule; see Section IV.E                         well protected as customers of all
                                       challenges in providing water that meets                (Compliance Schedules) for further                     systems, and (2) monitoring provisions
                                       regulatory standards for DBPs and other                 discussion. EPA has consulted with                     should be tailored to meet the first
                                       contaminants whose concentration can                    States and deferred to their expertise                 principle. Accordingly, the Advisory
                                       increase in the distribution system.                    regarding the nature of the connection                 Committee recommended that all
                                       Moreover, previous regulation of DBP                    in making combined distribution system                 wholesale and consecutive systems
                                       levels in consecutive systems varies                    determinations. In the absence of input                comply with provisions of the Stage 2
                                       widely among States. In consideration                   from the State, EPA will determine that                DBPR on the same schedule required of
                                       of these factors, EPA is finalizing                     combined distribution systems include                  the wholesale or consecutive system
                                       monitoring, compliance schedule, and                    all interconnected systems for the                     serving the largest population in the
                                       other requirements specifically for                     purpose of determining compliance                      combined distribution system. In
                                       consecutive systems. These                              schedules for implementation of this                   addition, the Advisory Committee
                                       requirements are intended to facilitate                 rule.                                                  recommended that EPA solicit
                                       compliance by consecutive systems                                                                              comments on issues related to
                                                                                               2. Background and Analysis
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                                       with MCLs for TTHM and HAA5 under                                                                              consecutive systems that the Advisory
                                       the Stage 2 DBPR and help to ensure                       The practice of public water systems                 Committee had not fully explored
                                       that consumers in consecutive systems                   buying and selling water to each other                 (USEPA 2000a). EPA agreed with these
                                       receive equivalent public health                        has been commonplace for many years.                   recommendations and they are reflected
                                       protection.                                             Reasons include saving money on                        in today’s rule.

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                                       3. Summary of Major Comments                            systems have only a marginal                           under the Initial Distribution System
                                          Commenters generally supported the                   association (such as an infrequently                   Evaluation (IDSE) or using existing
                                       proposed definitions. However,                          used emergency connection) with other                  Stage 1 DBPR compliance monitoring
                                       commenters did express some concerns,                   systems in the combined distribution                   locations (as discussed in Section IV.F).
                                       especially with including a time period                 system. To prepare for the IDSE and                    EPA has dropped the proposed phased
                                       of water delivery that defined whether                  subsequent Stage 2 implementation,                     approach for LRAA implementation
                                       a system was a consecutive system                       EPA has worked with States in                          (Stage 2A and Stage 2B) by removing
                                       (proposed to trigger plant-based                        identifying all systems that are part of               Stage 2A and redesignating Stage 2B as
                                       monitoring requirements) or wholesale                   each combined distribution system.                     Stage 2.
                                       system (proposed to allow                                  Finally, several commenters requested
                                                                                               that the wholesale system definition                     Details of monitoring requirements
                                       determination that a combined                                                                                  and compliance schedules are discussed
                                       distribution system existed). EPA has                   replace ‘‘public water system’’ with
                                                                                               ‘‘water system’’ so that wholesale                     in preamble Sections IV.G and IV.E,
                                       dropped this requirement from the final                                                                        respectively, and may be found in
                                       rule; population-based monitoring                       systems serving fewer than 25 people
                                                                                               would not be considered public water                   subpart V of today’s rule.
                                       requirements in the final rule do not
                                       need to define how long a plant must                    systems. EPA did not change the                        2. Background and Analysis
                                       operate in order to be considered a                     definition in today’s rule; EPA considers
                                       plant, and EPA has provided some                        any water system to be a public water                     The MCLs for TTHM and HAA5 are
                                       flexibility for States to determine which               system (PWS) if it serves 25 or more                   the same as those proposed, 0.080 mg/
                                       systems comprise a combined                             people either directly (retail) or                     L TTHM and 0.060 mg/L HAA5 as an
                                       distribution system (without presenting                 indirectly (by providing finished water                LRAA. See the proposed rule (68 FR
                                       a time criterion).                                      to a consecutive system) or through a                  49584, August 18, 2003) (USEPA 2003a)
                                          Other commenters expressed concern                   combination of retail and consecutive                  for a more detailed discussion of the
                                       that the proposed definition of                         system customers. If a PWS receives                    analysis supporting the MCLs. The
                                       consecutive system was inconsistent                     water from an unregulated entity, that                 primary objective of the LRAA is to
                                       with use of the term prior to the                       PWS must meet all compliance                           reduce exposure to high DBP levels. For
                                       rulemaking. EPA acknowledges that the                   requirements (including monitoring and                 an LRAA, an annual average must be
                                       Agency has not previously formally                      treatment techniques) that any other                   computed at each monitoring location.
                                       defined the term, but believes that the                 public water system that uses source                   The RAA compliance basis of the 1979
                                       definition in today’s rule best considers               water of unknown quality must meet.                    TTHM rule and the Stage 1 DBPR allows
                                       all commenters’ concerns, while also                    C. LRAA MCLs for TTHM and HAA5                         a system-wide annual average under
                                       providing for accountability and public                                                                        which high DBP concentrations in one
                                       health protection in as simple a manner                 1. Today’s Rule                                        or more locations are averaged with, and
                                       as is possible given the many                              This rule requires the use of                       dampened by, lower concentrations
                                       consecutive system scenarios that                       locational running annual averages                     elsewhere in the distribution system.
                                       currently exist.                                        (LRAAs) to determine compliance with                   Figure IV.C–1 illustrates the difference
                                          Several States requested flexibility to              the Stage 2 MCLs of 0.080 mg/L TTHM                    in calculating compliance with the
                                       determine which systems comprised a                     and 0.060 mg/L HAA5. All systems,                      MCLs for TTHM between a Stage 1
                                       combined distribution system under                      including consecutive systems, must                    DBPR RAA, and the Stage 2 DBPR
                                       this rule; EPA has included that                        comply with the MCLs for TTHM and                      LRAA.
                                       flexibility for situations in which                     HAA5 using sampling sites identified                   BILLING CODE 6560–50–P
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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                         411

                                       BILLING CODE 6560–50–C
                                                                                               the expected impact on the water                       requirements. In the process of
                                          EPA and the Stage 2 M–DBP Advisory                   industry and its customers. Strategies                 evaluating alternatives, EPA and the
                                       Committee considered an array of                        considered included across the board                   Advisory Committee reviewed vast
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                                       alternative MCL strategies. The                         requirements, such as significantly                    quantities of data and many analyses
                                       Advisory Committee discussions                          decreasing the MCLs (e.g., 40/30) or                   that addressed health effects, DBP
                                       primarily focused on the relative                       single hit MCLs (e.g., all samples must                occurrence, predicted reductions in DBP
                                       magnitude of exposure reduction versus                  be below 80/60); and risk targeting                    levels, predicted technology changes,

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                                       and capital, annual, and household                      systems are able to comply with an RAA                 level suggested by the consecutive
                                       costs. The Advisory Committee                           MCL even if they have a plant with a                   systems, and the time and money it
                                       recommended and EPA proposed the                        poor quality water source (that thus                   could take to work out differences.
                                       risk targeting approach of 80/60 as an                  produces high concentrations of DBPs)                  Although setting up a contract is a
                                       LRAA preceded by an IDSE. Today’s                       because they have another plant that has               prudent business action, commenters
                                       rule finalizes these requirements.                      a better quality water source (and thus                noted that small consecutive water
                                          EPA has chosen compliance based on                   lower concentrations of DBPs).                         systems have few resources to sue for
                                       an LRAA due to concerns about levels                    Individuals served by the plant with the               damages should the wholesaler provide
                                       of DBPs above the MCL in some                           poor quality source will usually have                  water exceeding the MCL.
                                       portions of the distribution system. The                higher DBP exposure than individuals                     The purpose of DBPRs is to protect
                                       LRAA standard will eliminate system-                    served by the other plant.                             public health from exposure to high
                                       wide averaging of monitoring results                       In part, both the TTHM and HAA5                     DBP levels. Not requiring violations
                                       from different monitoring locations. The                classes are regulated because they occur               when distributed water exceeds MCLs
                                       individuals served in areas of the                      at high levels and represent chlorination              undermines the intent of the rule. While
                                       distribution system with above average                  byproducts that are produced from                      EPA recognizes consecutive systems do
                                       DBP occurrence levels masked by                         source waters with a wide range of                     not have full control over the water they
                                       averaging under an RAA are not                          water quality. The combination of                      receive, agreements between wholesale
                                       receiving the same level of health                      TTHM and HAA5 represent a wide                         and consecutive systems may specify
                                       protection. Although an LRAA standard                   variety of compounds resulting from                    water quality and actions required of the
                                       still allows averaging at a single location             bromine substitution and chlorine                      wholesaler if those water quality
                                       over an annual period, EPA concluded                    substitution reactions (e.g., bromoform                standards are not met.
                                       that changing the basis of compliance                   has three bromines, TCAA has three
                                       from an RAA to an LRAA will result in                   chlorines, BDCM has one bromine and                      Finally, commenters recommended
                                       decreased exposure to higher DBP levels                 two chlorines). EPA believes that the                  that the Stage 2A provisions in the
                                       (see Section VI for predictions of DBP                  TTHM and HAA5 classes serve as an                      proposed rule be removed. These
                                       reductions under the LRAA MCLs). This                   indicator for unidentified and                         provisions (compliance with locational
                                       conclusion is based on three                            unregulated DBPs. EPA believes that                    running annual average MCLs of 0.120
                                       considerations:                                         controlling the occurrence levels of                   mg/L for TTHM and 0.100 mg/L for
                                          (1) There is considerable evidence                   TTHM and HAA5 will help control the                    HAA5) required systems to comply with
                                       that under the current RAA MCL                          overall levels of chlorination DBPs.                   the Stage 1 MCLs (as running annual
                                       compliance monitoring requirements, a                                                                          averages) and the Stage 2A MCLs (as
                                       small but significant proportion of                     3. Summary of Major Comments                           LRAAs) concurrently until systems were
                                       monitoring locations experience high                       Commenters supported the proposed,                  required to comply with Stage 2B MCLs.
                                       DBP levels at least some of the time. Of                risk-targeted MCL strategy over the                    Commenters noted that having two
                                       systems that collected data under the                   alternative MCL strategies that were                   separate MCLs for an individual system
                                       Information Collection Rule that met the                considered by the Advisory Committee                   to comply with at the same time was
                                       Stage 1 DBPR RAA MCLs, 14 percent                       as the preferred regulatory strategy.                  confusing to the system and its
                                       had TTHM single sample concentrations                   Commenters concurred with EPA’s                        customers. In addition, State resources
                                       greater than the Stage 1 MCL, and 21                    analysis that such an approach will                    needed for compliance determinations
                                       percent had HAA5 single sample                          reduce peak and average DBP levels.                    and data management for this short-term
                                       concentrations above the MCL.                           Commenters supported the Stage 2 long-                 requirement would be resource-
                                       Although most TTHM and HAA5                             term MCLs of 0.080 mg/L TTHM and                       intensive. Finally, resources spent to
                                       samples were below 100 µg/L, some                       0.060 mg/L HAA5 as LRAAs.                              comply with Stage 2A would be better
                                       ranged up to 140 µg/L and 130 µg/L,                        EPA received many comments on                       spent in complying with Stage 2B,
                                       respectively.                                           today’s MCLs specific to consecutive                   especially given that some of the
                                          (2) In some situations, the populations              systems. While commenters supported                    changes for Stage 2A compliance might
                                       served by certain portions of the                       consecutive system compliance with the                 not provide any benefit for Stage 2B.
                                       distribution system consistently receive                Stage 2 DBPR in order to provide                       Since EPA agrees with commenters’
                                       water that exceeds 0.080 mg/L for                       comparable levels of public health                     concerns, the Stage 2A requirements
                                       TTHM or 0.060 mg/L for HAA5 (both as                    protection, they noted that it would be                have been removed from the final rule.
                                       LRAAs) even though the system is in                     difficult for many consecutive systems
                                                                                                                                                      D. BAT for TTHM and HAA5
                                       compliance with Stage 1 MCLs). Of                       to meet Stage 2 requirements because
                                       Information Collection Rule systems                     they have not had to meet the full scope               1. Today’s Rule
                                       meeting the Stage 1 DBPR MCLs as                        of DBP requirements under previous
                                       RAAs, five percent had monitoring                       rules. EPA has developed a training and                   Today, EPA is identifying the best
                                       locations that exceeded 0.080 mg/L                      outreach program to assist these systems               available technology (BAT) for the
                                       TTHM and three percent exceeded                         and encourages States, wholesale                       TTHM and HAA5 LRAA MCLs (0.080
                                       0.060 mg/L HAA5 as an annual average                    systems, and professional associations                 mg/L and 0.060 mg/L respectively) for
                                       (i.e., as LRAAs) by up to 25%                           to also provide assistance.                            systems that treat their own source
                                       (calculated as indicated in Figure IV.C–                   Some commenters expressed concern                   water as one of the three following
                                       1). Customers served at these locations                 about holding consecutive systems                      technologies:
                                       consistently received water with TTHM                   responsible for water quality over which                  (1) GAC10 (granular activated carbon
                                       and/or HAA5 concentrations higher                       they have no control. Several                          filter beds with an empty-bed contact
                                       than the system-wide average and                        commenters were concerned about the                    time of 10 minutes based on average
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                                       higher than the MCL.                                    establishment of contracts between                     daily flow and a carbon reactivation
                                          (3) Compliance based on an LRAA                      wholesale and consecutive systems,                     frequency of every 120 days)
                                       will remove the opportunity for systems                 including concern about a strain on                       (2) GAC20 (granular activated carbon
                                       to average out samples from high and                    their relationship, wholesale system                   filter beds with an empty-bed contact
                                       low quality water sources. Some                         reluctance to commit to keep DBPs at a                 time of 20 minutes based on average

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                                       daily flow and a carbon reactivation                           conducted an Information Collection                     membrane process. Also, nanofiltration
                                       frequency of every 240 days)                                   Rule GAC treatment study,                               is an accepted technology for treatment
                                          (3) Nanofiltration (NF) using a                             approximately 70 percent of the surface                 of high TOC ground waters in Florida
                                       membrane with a molecular weight                               water plants studied could meet the                     and parts of the Southwest, areas of the
                                       cutoff of 1000 Daltons or less.                                0.080 mg/L TTHM and 0.060 mg/L                          country with elevated TOC levels in
                                          EPA is specifying a different BAT for                       HAA5 MCLs, with a 20 percent safety                     ground waters.
                                       consecutive systems than for systems                           factor (i.e., 0.064 mg/L and 0.048 mg/L,                   The second method that EPA used to
                                       that treat their own source water to meet                      respectively) using GAC with 10                         examine alternatives for BAT was the
                                       the TTHM and HAA5 LRAA MCLs. The                               minutes of empty bed contact time and                   Surface Water Analytical Tool model
                                       consecutive system BAT is                                      a 120 day reactivation frequency, and 78                that was developed to compare
                                       chloramination with management of                              percent of the plants could meet the                    alternative regulatory strategies as part
                                       hydraulic flow and storage to minimize                         MCLs with a 20 percent safety factor                    of the Stage 1 and Stage 2 M–DBP
                                       residence time in the distribution                             using GAC with 20 minutes of empty                      Advisory Committee deliberations. EPA
                                       system for systems that serve at least                         bed contact time and a 240 day                          modeled a number of BAT options. In
                                       10,000 people and management of                                reactivation frequency. Because the                     the model, GAC10 was defined as
                                       hydraulic flow and storage to minimize                         treatment studies were conducted at                     granular activated carbon with an empty
                                       residence time in the distribution                             plants with much poorer water quality                   bed contact time of 10 minutes and a
                                       system for systems that serve fewer than                       than the national average, EPA believes                 reactivation or replacement interval of
                                       10,000 people.                                                 that much higher percentages of plants                  90 days or longer. GAC20 was defined
                                       2. Background and Analysis                                     nationwide could meet the MCLs with                     as granular activated carbon with an
                                                                                                      the proposed GAC BATs.                                  empty bed contact time of 20 minutes
                                          The BATs are the same as was
                                       proposed, except that consecutive                                 Among plants using GAC, larger                       and a reactivation or replacement
                                       systems serving fewer than 10,000                              systems would likely realize an                         interval of 90 days or longer.
                                       people do not have chloramination as                           economic benefit from on-site                              The compliance percentages
                                       part of the consecutive system BAT. See                        reactivation, which could allow them to                 forecasted by the SWAT model are
                                       the proposal (68 FR 49588, August 18,                          use smaller, 10-minute empty bed                        indicated in Table IV.D–1. EPA
                                       2003) (USEPA 2003a) for more detail on                         contact time contactors with more                       estimates that more than 97 percent of
                                       the analysis supporting these                                  frequent reactivation (i.e., 120 days or                large systems will be able to achieve the
                                       requirements. The Safe Drinking Water                          less). Most small systems would not                     Stage 2 MCLs with the GAC BAT,
                                       Act directs EPA to specify BAT for use                         find it economically advantageous to                    regardless of post-disinfection choice
                                       in achieving compliance with the MCL.                          install on-site carbon reactivation                     (Seidel Memo, 2001). Because the
                                       Systems unable to meet the MCL after                           facilities, and thus would opt for larger,              source water quality (e.g., DBP
                                       application of BAT can get a variance                          20-minute empty bed contact time                        precursor levels) in medium and small
                                       (see Section IV.K for a discussion of                          contactors, with less frequent carbon                   systems is expected to be comparable to
                                       variances). Systems are not required to                        replacement (i.e., 240 days or less).                   or better than that for the large system
                                       use BAT in order to comply with the                               The Information Collection Rule                      (USEPA 2005f), EPA believes it is
                                       MCL. PWSs may use any State-approved                           treatment study results also                            conservative to assume that at least 90
                                       technologies as long as they meet all                          demonstrated that nanofiltration was                    percent of medium and small systems
                                       drinking water standards.                                      the better DBP control technology for                   will be able to achieve the Stage 2 MCLs
                                          EPA examined BAT options first by                           ground water sources with high TOC                      if they were to apply one of the
                                       analyzing data from the Information                            concentrations (i.e., above                             proposed GAC BATs. EPA assumes that
                                       Collection Rule treatment studies                              approximately 6 mg/L). The results of                   small systems may adopt GAC20 in a
                                       designed to evaluate the ability of GAC                        the membrane treatment studies showed                   replacement mode (with replacement
                                       and NF to remove DBP precursors.                               that all ground water plants could meet                 every 240 days) over GAC10 because it
                                       Based on the treatment study results,                          the 0.080 mg/L TTHM and 0.060 mg/L                      may not be economically feasible for
                                       GAC is effective for controlling DBP                           HAA5 MCLs, with a 20% safety factor                     some small systems to install and
                                       formation for waters with influent TOC                         (i.e., 0.064 mg/L and 0.048 mg/L,                       operate an on-site GAC reactivation
                                       concentrations below approximately 6                           respectively) at the system average                     facility. Moreover, some small systems
                                       mg/L (based on the Information                                 distribution system residence time using                may find nanofiltration cheaper than the
                                       Collection Rule and NRWA data, over                            nanofiltration. Nanofiltration would be                 GAC20 in a replacement mode if their
                                       90 percent of plants have average                              less expensive than GAC for high TOC                    specific geographic locations cause a
                                       influent TOC levels below 6 mg/L                               ground waters, which generally require                  relatively high cost for routine GAC
                                       (USEPA 2003c)). Of the plants that                             minimal pretreatment prior to the                       shipment.

                                                         STAGE 2 MCLS AFTER APPLICATION OF SPECIFIED TREATMENT TECHNOLOGIES
                                                                                                  Compliance with 0.080 mg/L TTHM and 0.060                Compliance with 0.064 mg/L TTHM and 0.048
                                                                                                              mg/L HAA5 LRAAs                              mg/L HAA5 LRAAs (MCLs with 20% Safety fac-
                                                                                                      Residual disinfectant
                                                          Technology                                                                                                   Residual
                                                                                                                                          All systems                 disinfectant           All systems
                                                                                                 Chlorine (per-         Chloramine         (percent)                                          (percent)
                                                                                                     cent)               (percent)                         Chlorine (per-      Chloramine
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                                                                                                                                                               cent)            (percent)

                                       Enhanced Coagulation (EC) ....................                       73.5                76.9                74.8              57.2            65.4           60.4
                                       EC (no pre-disinfection) ...........................                 73.4                88.0                78.4              44.1            62.7           50.5
                                       EC & GAC10 ............................................              100                 97.1                99.1              100             95.7           98.6

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                                                     STAGE 2 MCLS AFTER APPLICATION OF SPECIFIED TREATMENT TECHNOLOGIES—Continued
                                                                                                  Compliance with 0.080 mg/L TTHM and 0.060                Compliance with 0.064 mg/L TTHM and 0.048
                                                                                                              mg/L HAA5 LRAAs                              mg/L HAA5 LRAAs (MCLs with 20% Safety fac-
                                                                                                      Residual disinfectant
                                                          Technology                                                                                                   Residual
                                                                                                                                          All systems                 disinfectant           All systems
                                                                                                 Chlorine (per-         Chloramine         (percent)                                          (percent)
                                                                                                     cent)               (percent)                         Chlorine (per-      Chloramine
                                                                                                                                                               cent)            (percent)

                                       EC & GAC20 ............................................               100                 100                 100               100            100             100
                                       EC & All Chloramines ..............................                    NA                83.9                  NA               NA             73.6            NA
                                          Note: Enhanced coagulation/softening is required under the Stage 1 DBPR for conventional plants.
                                          Source: Seidel (2001).

                                          The BAT requirements for large                                EPA believes that the BATs for                        contradicts the premise of the Stage 1
                                       consecutive systems are the same as                            nonconsecutive systems are not                          DBPR that DBPs are best controlled
                                       proposed, but the requirements have                            appropriate for consecutive systems                     through TOC removal and optimizing
                                       changed for small consecutive systems.                         because their efficacy in controlling                   disinfection processes, the SDWA
                                       EPA believes that the best compliance                          DBPs is based on precursor removal.                     requires EPA to identify a BAT for all
                                       strategy for consecutive systems is to                         Consecutive systems face the unique                     systems required to meet an MCL. No
                                       collaborate with wholesalers on the                            challenge of receiving waters in which                  commenter recommended an alternative
                                       water quality they need. For consecutive                       DBPs are already present if the                         BAT. EPA still believes that precursor
                                       systems that are having difficulty                             wholesale system has used a residual                    removal remains a highly effective
                                       meeting the MCLs, EPA is specifying a                          disinfectant, which the BATs for non-                   strategy to reduce DBPs. Thus, EPA
                                       BAT of chloramination with                                     consecutive systems do not effectively                  encourages States to work with
                                       management of hydraulic flow and                               remove. GAC is not cost-effective for                   wholesale systems and consecutive
                                       storage to minimize residence time in                          removing DBPs. Nanofiltration is only                   systems to identify strategies to ensure
                                       the distribution system for systems                            moderately effective at removing THMs                   compliance, especially those systems
                                       serving at least 10,000 and management                         or HAAs if membranes with a very low                    with DBP levels close to the MCL.
                                       of hydraulic flow and storage to                               molecular weight cutoff (and very high
                                       minimize residence time in the                                                                                         E. Compliance Schedules
                                                                                                      cost of operation are employed).
                                       distribution system for systems serving                        Therefore, GAC and nanofiltration are                   1. Today’s Rule
                                       fewer than 10,000. EPA believes that                           not appropriate BATs for consecutive
                                       small consecutive systems can use this                                                                                   This section specifies compliance
                                       BAT to comply with the Stage 2 DBPR,                                                                                   dates for the IDSE and MCL compliance
                                       but if they cannot, then they can apply                        3. Summary of Major Comments                            requirements in today’s rule. As
                                       to the State for a variance.                                      Commenters concurred with EPA’s                      described elsewhere in Section IV of
                                          Chloramination has been used for                            identification of BATs for non-                         this preamble, today’s rule requires
                                       residual disinfection for many years to                        consecutive systems but expressed                       PWSs to carry out the following
                                       minimize the formation of chlorination                         concern about the BAT for consecutive                   activities:
                                       DBPs, including TTHM and HAA5                                  systems. Many commenters agreed that                      • Conduct initial distribution system
                                       (USEPA 2003d). EPA estimates that over                         Stage 2 compliance for consecutive                      evaluations (IDSEs) on a required
                                       50 percent of large subpart H systems                          systems would usually best be achieved                  schedule. Systems may comply by using
                                       serving at least 10,000 use                                    by improved treatment by the wholesale                  any of four approaches for which they
                                       chloramination for Stage 1. The BAT                            system. However, they noted that the                    qualify (standard monitoring, system
                                       provision to manage hydraulic flow and                         proposed BAT may not be practical for                   specific study, 40/30 certification, or
                                       minimize residence time in the                                 compliance if water delivered to the                    very small system waiver).
                                       distribution system is to facilitate the                       consecutive system is at or near DBP                      • Determine Stage 2 monitoring
                                       maintenance of the chloramine residual                         MCLs. In addition, chloramination                       locations based on the IDSE.
                                       and minimize the likelihood for                                requires operator supervision and                         • Comply with Stage 2 MCLs on a
                                       nitrification. EPA has not included                            adjustment and many consecutive                         required schedule.
                                       chloramination for consecutive systems                         systems that buy water may be reluctant                   Compliance dates for these activities
                                       as part of the BAT for systems serving                         to operate chemical feed systems.                       vary by PWS size. Table IV.E–1 and
                                       fewer than 10,000 due to concerns about                        Therefore, EPA included chloramines as                  Figure IV.E–1 specify IDSE and Stage 2
                                       their ability to properly control the                          part of the BAT in today’s rule only for                compliance dates. Consecutive systems
                                       process, given that many have no                               systems serving at least 10,000 because                 of any size must comply with the
                                       treatment capability or expertise and the                      of the operator attention it requires and               requirements of the Stage 2 DBPR on the
                                       Agency’s concern about such systems                            concerns with safety and nitrification.                 same schedule as required for the largest
                                       having operational difficulties such as                        While some commenters believed that                     system in the combined distribution
                                       distribution system nitrification.                             having a BAT for consecutive systems                    system.
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                                                                                   TABLE IV.E–1.—IDSE AND STAGE 2 COMPLIANCE DATES
                                                                                                              Compliance dates by PWS size (retail population served) 1

                                                  Requirement                        CWSs and                   CWSs and                     CWSs and              CWSs serving          NTNCWSs serving
                                                                                 NTNCWSs serving             NTNCWSs serving              NTNCWSs serving            <10,000                <10,000
                                                                                  at least 100,000            50,000–99,999                10,000–49,999

                                       Submit IDSE monitoring plan OR           October 1, 2006 .....       April 1, 2007 ...........   October 1, 2007 .....    April 1, 2008 .......   Not applicable.
                                       Submit IDSE system specific
                                         study plan OR.
                                       Submit 40/30 certification OR .....
                                       Receive very small system waiv-
                                         er from State.
                                       Complete standard monitoring or          September 30, 2008          March 31, 2009 ......       September 30, 2009       March 31, 2010 ..       Not applicable.
                                         system specific study.
                                       Submit IDSE Report ...................   January 1, 2009 .....       July 1, 2009 ............   January 1, 2010 .....    July 1, 2010 .......    Not applicable.
                                       Begin subpart V (Stage 2) com-           April 1, 2012 ...........   October 1, 2012 .....       October 1, 2013 .....    October 1, 2013
                                         pliance monitoring 2.                                                                                                     (October 1,
                                                                                                                                                                   2014 if Crypto-
                                                                                                                                                                   sporidium mon-
                                                                                                                                                                   itoring is re-
                                                                                                                                                                   quired under
                                                                                                                                                                   Subpart W)..
                                         1 Wholesale and consecutive systems that are part of a combined distribution system must comply based on the schedule required of the larg-
                                       est system in the combined distribution system.
                                         2 States may grant up to an additional 2 years for systems making capital improvements.

                                       BILLING CODE 6560–50–P
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                                       BILLING CODE 6560–50–C

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                                       2. Background and Analysis                              locations and schedules to the State or                requiring IDSE plan review prior to
                                          The compliance schedule in today’s                   primacy agency. Where required, PWSs                   conducting the IDSE.
                                       final rule stems from the risk-targeted                 must provide the necessary level of                       • Provides additional time to develop
                                       approach of the rule, wherein PWSs                      treatment to comply with the Stage 2                   budgets and establish contracts with
                                       conduct initial monitoring to determine                 MCLs within three years of the                         laboratories.
                                                                                               completion of State or primacy agency
                                       locations and concentrations of high
                                                                                               review of the IDSE report, though States                  • Spreads out the workload for
                                       DBPs. A primary objective of this                                                                              technical assistance and guidance. The
                                                                                               may allow an additional two years for
                                       schedule is to ensure that PWSs identify                                                                       staggered schedule will allow States and
                                                                                               PWSs making capital improvements.
                                       locations with high DBP concentrations                     EPA has modified the proposed                       EPA to provide more support to
                                       and provide appropriate additional                      compliance schedule to stagger                         individual PWSs as needed.
                                       treatment in a timely manner for high                   monitoring start dates for PWSs serving                   • Provides time for DBP analytical
                                       risk areas, while not requiring low risk                10,000 to 99,999 people and to allow                   laboratories to build capacity as needed
                                       systems to add additional treatment.                    more time for development and review                   to accommodate the sample analysis
                                       The compliance schedule balances the                    of IDSE monitoring plans prior to the                  needs of PWSs and extends and
                                       objective of early risk-targeted                        start of monitoring. The following                     smooths the demand for laboratory
                                       monitoring with adequate time for                       discussion addresses these changes from                services.
                                       PWSs and the State or primacy agency                    the proposal.
                                       to assure full implementation and                                                                                 • Maintains simultaneous rule
                                                                                                  The proposed rule required all PWSs                 compliance with the LT2ESWTR as
                                       compliance. EPA is establishing                         serving at least 10,000 people (plus
                                       concurrent compliance schedules under                                                                          recommended by the Stage 2 M-DBP
                                                                                               smaller systems that are part of a                     Advisory Committee and as mandated
                                       the Stage 2 DBPR for all systems (both                  combined distribution system with a
                                       wholesale systems and consecutive                                                                              by the 1996 SDWA Amendments, which
                                                                                               PWS that serves at least 10,000 people)                require that EPA ‘‘minimize the overall
                                       systems) in a particular combined                       to complete IDSE monitoring and
                                       distribution system because this will                                                                          risk of adverse health effects by
                                                                                               submit IDSE reports (including                         balancing the risk from the contaminant
                                       assure comparable risk-based targeting                  recommended Stage 2 compliance
                                       information being available at the same                                                                        and the risk from other contaminants
                                                                                               monitoring locations) two years after                  the concentrations of which may be
                                       time for all PWSs that are part of a                    rule promulgation, followed by one year
                                       combined distribution system and                                                                               affected by the use of a treatment
                                                                                               for review of IDSE reports, after which
                                       thereby allow for more cost-effective                                                                          technique or process that would be
                                                                                               systems had three years to come into
                                       compliance with TTHM and HAA5                                                                                  employed to attain the maximum
                                                                                               compliance with Stage 2B MCLs.
                                       MCLs.                                                      Under today’s final rule, PWSs                      contaminant level’’ (Sec.
                                          SDWA section 1412(b)(10) states that                 serving at least 100,000 people (plus                  1412(b)(5)(B)(i)).
                                       a drinking water regulation shall take                  smaller systems that are part of the                      The Advisory Committee
                                       effect 3 years from the promulgation                    combined distribution system) will meet                recommended the Initial Distribution
                                       date unless the Administrator                           the same Stage 2 compliance deadlines
                                                                                                                                                      System Evaluation, as discussed in
                                       determines that an earlier date is                      as proposed. However, the timing of the
                                                                                                                                                      Section IV.F, and EPA is finalizing an
                                       practicable. Today’s rule requires PWSs                 IDSE has been changed to allow for a
                                                                                                                                                      IDSE schedule generally consistent with
                                       to begin monitoring prior to 3 years                    more even workload and a greater
                                                                                                                                                      the Advisory Committee timeframe
                                       from the promulgation date. Based on                    opportunity for primacy agency
                                                                                                                                                      recommendation, but modified to
                                       EPA’s assessment and recommendations                    involvement (e.g., through monitoring
                                                                                                                                                      stagger the schedule for systems serving
                                       of the Advisory Committee, as described                 plan review and approval). The IDSE
                                                                                                                                                      more than 10,000 but less than 100,000,
                                       in this section, EPA has determined that                plan submission dates for PWSs serving
                                                                                                                                                      and to address public comments on the
                                       these monitoring start dates are                        50,000 to 99,999 people (plus smaller
                                                                                                                                                      IDSE requirements.
                                       practicable and appropriate.                            systems that are part of the combined
                                          Systems must submit their IDSE plans                 distribution system) will be 12 months                    For all systems, the IDSE schedule has
                                       (monitoring plans for standard                          after the effective date; for PWSs serving             been revised to allow systems to submit
                                       monitoring, study plans for system                      10,000 to 49,999 (plus smaller systems                 and States or primacy agencies to
                                       specific studies) to the primacy agency                 that are part of the combined                          review (and revise, if necessary)
                                       for review and approval. The State or                   distribution system), the IDSE plan                    systems’ recommendations for IDSE and
                                       primacy agency will then have 12                        submission dates will be 18 months                     Stage 2 monitoring locations, while still
                                       months to review, and, as necessary,                    after the effective date. The Stage 2                  allowing systems three years after
                                       consult with the system. A number of                    compliance schedule for systems                        completion of the State or primacy
                                       PWSs will then conduct one year of                      serving fewer than 10,000 people                       agency review of Stage 2 compliance
                                       distribution system monitoring for                      remains the same as proposed. Stage 2                  monitoring locations to make necessary
                                       TTHM and HAA5 at locations other                        MCL compliance dates are modified                      treatment and operational changes to
                                       than those currently used for Stage 1                   accordingly.                                           comply with Stage 2 MCLs.
                                       DBPR compliance monitoring. At the                         This staggering of IDSE start dates for                Figure IV.E–2 illustrates compliance
                                       conclusion of this monitoring, these                    PWSs serving 10,000 to 99,999 people is                schedules for examples of three
                                       PWSs have three months to evaluate                      advantageous in several respects:                      combined distribution systems, with the
                                       analysis and monitoring results and                        • Provides PWSs greater assurance                   schedule dictated by the retail
                                       submit Stage 2 compliance monitoring                    that IDSEs are properly conducted by                   population served by the largest system.

                                                                                              FIGURE IV.E–2.—SCHEDULE EXAMPLES.
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                                       —Wholesale system (pop. 64,000) with three consecutive systems (pops. 21,000; 15,000; 5,000):
                                         —IDSE monitoring plan due for all systems April 1, 2007 since wholesale system serves 50,000–99,999
                                         —Stage 2 compliance beginning October 1, 2012 for all systems
                                       —Wholesale system (pop. 4,000) with three consecutive systems (pops. 21,000; 5,000; 5,000):

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                                                                                      FIGURE IV.E–2.—SCHEDULE EXAMPLES.—Continued
                                         —IDSE monitoring plan due for all systems October 1, 2007 since the largest system in combined distribution system serves 10,000–
                                         —Stage 2 compliance beginning October 1, 2013 for all systems
                                       —Wholesale system (pop. 4,000) with three consecutive systems (pops. 8,000; 5,000; 5,000):
                                         —IDSE monitoring plan due for all systems April 1, 2008 since no individual system in combined distribution system exceeds 10,000 (even
                                           though total population exceeds 10,000)
                                         —Stage 2 compliance beginning October 1, 2013 if no Cryptosporidium monitoring under the LT2ESWTR is required or beginning October
                                           1, 2014 if Cryptosporidium monitoring under the LT2ESWTR is required

                                          This schedule requires wholesale                     the August 18, 2003 proposal. Major                    a larger system in their combined
                                       systems and consecutive systems that                    issues raised by commenters include                    distribution system, do not begin
                                       are part of a combined distribution                     providing more time for PWSs to                        monitoring until more than 36 months
                                       system with at least one system with an                 prepare for monitoring, giving States or               after the effective date.
                                       earlier compliance deadline to conduct                  primacy agencies more time to oversee                     EPA believes that the final
                                       their IDSE simultaneously so that the                   monitoring, and establishing consistent                compliance schedule allows PWSs
                                       wholesale system will be aware of                       schedules for consecutive PWSs. A                      sufficient time to develop IDSE plans
                                       compliance challenges facing the                        summary of these comments and EPA’s                    with these compliance dates. The
                                       consecutive systems and will be able to                 responses follows.                                     schedule also allows 12 months for
                                       implement treatment plant, capital, and                    Standard monitoring plan and system                 State or primacy agency review of IDSE
                                       operational improvements as necessary                   specific study plan preparation. Many                  plans, which allows additional time for
                                       to ensure compliance of both the                        commenters were concerned about the                    review and for coordination with
                                       wholesale and consecutive systems. The                  proposed requirement to develop and                    systems and provides more time to
                                       Advisory Committee and EPA both                         execute an IDSE monitoring plan                        address deficiencies in IDSE plans. This
                                       recognized that DBPs, once formed, are                  without any primacy agency review.                     is especially important for smaller
                                       difficult to remove and are generally                   PWSs specifically expressed concern                    PWSs, which are likely to need the most
                                       best addressed by treatment plant                       about the financial commitment without                 assistance from States. By staggering
                                       improvements, typically through                         prior State approval and noted that                    monitoring start dates, today’s rule also
                                       precursor removal or use of alternative                 some PWSs would need more than the                     eases implementation by reducing the
                                       disinfectants. For a wholesale system to                time allowed under the proposed rule to                number of PWSs that will submit plans
                                       make the best decisions concerning the                  develop and implement an IDSE                          at any one time, when the most
                                       treatment steps necessary to meet                       monitoring plan, especially without an                 assistance from regulatory agencies will
                                       TTHM and HAA5 LRAAs under the                           opportunity for State or primacy agency                be required.
                                       Stage 2 DBPR, both in its own                           review and approval. Smaller PWSs                         In summary, today’s schedule has
                                       distribution system and in the                          may require substantial time and                       been modified so that systems are
                                       distribution systems of consecutive                     planning to budget for IDSE expenses,                  required to submit IDSE plans for
                                       systems it serves, the wholesale system                 especially for systems that have not                   primacy agency review and approval
                                       must know the DBP levels throughout                     previously complied with DBP MCLs.                     prior to conducting their IDSE. Systems
                                       the combined distribution system.                          EPA recognizes these concerns and                   can consider that their plan has been
                                       Without this information, the wholesale                 today’s final rule provides time for                   approved if they have not heard back
                                       system may design treatment changes                     PWSs to submit IDSE plans (monitoring                  from the State by the end of the State
                                       that allow the wholesale system to                      plans, study plans, or 40/30                           review period. Systems are also required
                                       achieve compliance, but leave the                       certifications) for State or primacy                   to conduct the approved monitoring and
                                       consecutive system out of compliance.                   agency review and more time before                     submit their IDSE report (including the
                                          In summary, the compliance schedule                  having to begin monitoring.                            system’s recommended Stage 2
                                       for today’s rule maintains the earliest                 Specifically, PWSs serving 50,000 to                   compliance monitoring) for State or
                                       compliance dates recommended by the                     99,999 people and those serving 10,000                 primacy agency review on a schedule
                                       Advisory Committee for PWSs serving                     to 49,999 people must submit IDSE                      that allows for systems to still have a
                                       at least 100,000 people (plus smaller                   plans about 12 months and 18 months                    minimum of full three years to comply
                                       systems that are part of the combined                   after the effective date, respectively, and            with Stage 2 following State or primacy
                                       distribution system). These PWSs serve                  complete standard monitoring or a                      agency review of the system’s Stage 2
                                       the majority of people. The schedule                    system specific study within two years                 recommended monitoring. As with the
                                       also maintains the latest compliance                    after submitting their IDSE plan. This is              review of plans, systems can consider
                                       dates the Advisory Committee                            significantly more time than was                       that their IDSE report has been
                                       recommended, which apply to PWSs                        specified under the proposal, where                    approved if they have not heard back
                                       serving fewer than 10,000 people. EPA                   these systems would have had to                        from the State by the end of the State
                                       has staggered compliance schedules for                  conduct their IDSE and submit their                    review period.
                                       PWSs between these two size categories                  IDSE report 24 months after the effective                 State/primacy agency oversight. EPA
                                       in order to facilitate implementation of                date. PWSs serving at least 100,000                    is preparing to support implementation
                                       the rule. This staggered schedule is                    people must submit IDSE plans about                    of IDSE requirements that must be
                                       consistent with the schedule required                   six months after the effective date and                completed prior to States achieving
                                       under the LT2ESWTR promulgated                          complete standard monitoring or a                      primacy. Several States have expressed
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                                       elsewhere in today’s Federal Register.                  system specific study about 30 months                  concern about EPA providing guidance
                                                                                               after the effective date, which also                   and reviewing reports from systems that
                                       3. Summary of Major Comments                            provides more time than was specified                  the State has permitted, inspected, and
                                         EPA received significant public                       under the proposal. PWSs serving fewer                 worked with for a long time. These
                                       comment on the compliance schedule in                   than 10,000 people, not associated with                States believe that their familiarity with

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                                       the systems enables them to make the                    system (the interconnected distribution                F. Initial Distribution System Evaluation
                                       best decisions to implement the rule                    system consisting of the distribution                  (IDSE)
                                       and protect public health and that the                  systems of wholesale systems and of the                1. Today’s Rule
                                       rule requirement should be delayed                      consecutive systems that receive
                                       until States receive primacy.                           finished water) on the same Stage 2                       Today’s rule establishes requirements
                                       Commenters were concerned that some                     compliance schedule. Extending the                     for systems to perform an Initial
                                       States will not participate in early                    Stage 2 compliance dates would                         Distribution System Evaluation (IDSE).
                                       implementation activities and indicated                                                                        The IDSE is intended to identify sample
                                                                                               unnecessarily delay the public health
                                       that States would prefer monitoring to                                                                         locations for Stage 2 compliance
                                                                                               protection afforded by this rule.
                                       begin 24 months after rule                                                                                     monitoring that represent distribution
                                                                                               Consecutive systems must be able to
                                       promulgation. Commenters also noted                                                                            system sites with high DBP
                                                                                               evaluate whether wholesale system                      concentrations. Systems will develop an
                                       that States need sufficient time to                     changes are sufficient to ensure
                                       become familiar with the rule, train                                                                           IDSE plan, collect data on DBP levels
                                                                                               compliance and, if they are not, to make               throughout their distribution system,
                                       their staff, prepare primacy packages,
                                                                                               cost-effective changes to ensure                       evaluate these data to determine which
                                       and train PWSs.
                                          EPA agrees that State familiarity is an              compliance where wholesale system                      sampling locations are most
                                       important component of the review and                   efforts address some, but not all, of the              representative of high DBP levels, and
                                       approval process, looks forward to                      concerns with compliance. Public                       compile this information into a report
                                       working closely with the State drinking                 health protection through compliance                   for submission to the State or primacy
                                       water program representatives during                    with Stage 2 MCLs will occur on the                    agency. Systems must complete one
                                       IDSE implementation, and welcomes                       schedule of the largest system for all                 IDSE to meet the requirements of
                                       proactive State involvement. However,                   systems in the combined distribution                   today’s rule.
                                       the Agency believes that delaying                       system (regardless of size). If a                         a. Applicability. This requirement
                                       implementation of risk-based IDSE                       consecutive system must make capital                   applies to all community water systems,
                                       targeting activities until States receive               improvements to comply with this rule,                 and to large nontransient
                                       primacy is an unacceptable delay in                     the State may use its existing authority               noncommunity water systems (those
                                       public health protection and also                       to grant up to an additional 24 months                 serving at least 10,000 people) that use
                                       inconsistent with the Advisory                          to that system. In addition,                           a primary or residual disinfectant other
                                       Committee’s recommendations. EPA                        implementation and data tracking will                  than ultraviolet light, or that deliver
                                       remains committed to working with                       be simplified because all systems in a                 water that has been treated with a
                                       States to the greatest extent feasible to               combined distribution system will be on                primary or residual disinfectant other
                                       implement today’s rule, consistent with                                                                        than ultraviolet light. Systems serving
                                                                                               the same IDSE and Stage 2 compliance
                                       the schedule promulgated today. For                                                                            fewer than 500 people are covered by
                                                                                               schedule. EPA believes that this is a
                                       States unable to actively participate in                                                                       the very small system waiver provisions
                                                                                               better approach from both a public
                                       IDSE implementation, however, EPA                                                                              of today’s rule and are not required to
                                                                                               health standpoint and an                               complete an IDSE if they have TTHM
                                       believes it has an obligation to provide                implementation standpoint.
                                       support and guidance to PWSs who are                                                                           and HAA5 data collected under Subpart
                                       covered and independently responsible                      EPA agrees with many commenters                     L. Consecutive systems are subject to
                                       for complying with the IDSE                             that a high level of coordination among                the IDSE requirements of today’s rule.
                                       requirements of today’s rule and is                     wholesaler, consecutive system, and                    Consecutive systems must comply with
                                       prepared to oversee implementation.                     States will be necessary to ensure                     IDSE requirements on the same
                                       Moreover, EPA believes that the                         compliance. The schedule in today’s                    schedule as the system serving the
                                       staggered compliance schedule in                        rule provides more time for planning,                  largest population in the combined
                                       today’s final rule will enhance States’                 reviewing, and conducting the IDSE                     distribution system, as described in
                                       ability to help implement the rule.                     than the schedule in the proposed rule,                section IV.E.
                                          Consecutive systems. Most                            which will allow more time for                            b. Data collection. For those systems
                                       commenters supported consecutive                        necessary coordination, including small                not receiving a very small system
                                       systems being on the same IDSE                          consecutive systems that need help in                  waiver, there are three possible
                                       schedule as wholesale systems,                          negotiations with their wholesale                      approaches by which a system can meet
                                       recognizing the benefits of treatment                   system. EPA will work with ASDWA                       the IDSE requirement.
                                       plant capital and operational                           and States to develop guidance to                         i. Standard monitoring. Standard
                                       improvements by the wholesale system                    facilitate wholesale/consecutive system                monitoring requires one year of DBP
                                       as the preferred method of DBP                          cooperation. This additional time and                  monitoring throughout the distribution
                                       compliance, with the timely collection                  the staggered schedule discussed in this               system on a specified schedule. Prior to
                                       of DBP data throughout the combined                     section also lessens the laboratory                    commencing standard monitoring,
                                       distribution system a key component.                                                                           systems must prepare a monitoring plan
                                                                                               burden associated with IDSE
                                       Several commenters preferred that                                                                              and submit it to the primacy agency for
                                       consecutive systems have a later Stage                                                                         review. The frequency and number of
                                       2 compliance date to allow for                             The staggered schedule also helps                   samples required under standard
                                       evaluation of whether wholesale system                  address commenter concerns about                       monitoring is determined by source
                                       treatment changes are adequate to                       evaluating combined distribution                       water type and system size. The number
                                       ensure compliance and to consider                       systems. Other commenters’ concerns                    of samples does not depend on the
                                       changes to water delivery specifications.               about time needed for developing                       number of plants per system. Section
                                          EPA disagrees with those commenters                  contracts between systems and for                      IV.G provides a detailed discussion of
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                                       recommending a different Stage 2                        planning, funding, and implementing                    the specific population-based
                                       compliance date and thus has                            treatment changes are addressed by not                 monitoring requirements for IDSE
                                       maintained the approach in the                          requiring Stage 2 compliance until at                  standard monitoring. Although standard
                                       proposal, which keeps all systems that                  least six years following rule                         monitoring results are not to be used for
                                       are part of a combined distribution                     promulgation.                                          determining compliance with MCLs,

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                                       systems are required to include                                           a wide range of sample sites                                    HAA5 monitoring violations during the
                                       individual sample results for the IDSE                                    representative of the entire distribution                       same period. The State or primacy
                                       results when determining the range of                                     system, including those judged to                               agency may require systems to submit
                                       TTHM and HAA5 levels to be reported                                       represent high TTHM and HAA5                                    compliance monitoring results,
                                       in their Consumer Confidence Report                                       concentrations, and (2) extended period                         distribution system schematics, or
                                       (see section IV.J).                                                       simulation hydraulic models that                                recommend subpart V compliance
                                          ii. System specific study. Under this                                  simulate water age in the distribution                          monitoring locations as part of the
                                       approach, systems may choose to                                           system, in conjunction with one round                           certification. This certification must be
                                       perform a system specific study based                                     of TTHM and HAA5 sampling.                                      kept on file and submitted to the State
                                       on earlier monitoring studies or                                            iii. 40/30 certification. Under this                          or primacy agency for review. Systems
                                       distribution system hydraulic models in                                   approach, systems must certify to their                         that qualify for reduced monitoring for
                                       lieu of standard monitoring. Prior to                                     State or primacy agency that every                              the Stage 1 DBPR during the two years
                                       commencing a system specific study,                                       individual compliance sample taken                              prior to the start of the IDSE may use
                                       systems must prepare a study plan and                                     under subpart L during the period                               results of reduced Stage 1 DBPR
                                       submit it to the primacy agency for                                       specified in Table IV.F–2 were less than                        monitoring to prepare the 40/30
                                       approval. The two options for system                                      or equal to 0.040 mg/L for TTHM and                             certification. The requirements for the
                                       specific studies are: (1) TTHM and                                        less than or equal to 0.030 mg/L for                            40/30 certification are listed in Table
                                       HAA5 monitoring data that encompass                                       HAA5, and that there were no TTHM or                            IV.F–1.

                                                                                                    TABLE IV.F–1.—40/30 CERTIFICATION REQUIREMENTS
                                       40/30 Certification Requirements ...                      • A certification that every individual compliance sample taken under subpart L during the period specified
                                                                                                   in Table IV.F–2 were less than or equal to 0.040 mg/L for TTHM and less than or equal to 0.030 mg/L
                                                                                                   for HAA5, and that there were no TTHM or HAA5 monitoring violations during the same period.
                                                                                                 • Compliance monitoring results, distribution system schematics, and/or recommended subpart V compli-
                                                                                                   ance monitoring locations as required by the State or primacy agency.

                                                                                                               TABLE IV.F–2.—40/30 ELIGIBILITY DATES
                                                                                                                                                      Then your eligibility for 40/30 certification is based on eight consecutive
                                                                     If your 40/30 Certification Is Due                                               calendar quarters of subpart L compliance monitoring results beginning
                                                                                                                                                                                    no earlier than1

                                       (1)   October 1, 2006 ..................................................................................       January     2004.
                                       (2)   April 1, 2007 ........................................................................................   January     2004.
                                       (3)   October 1, 2007 ..................................................................................       January     2005.
                                       (4)   April 1, 2008 ........................................................................................   January     2005.
                                         1 Unless you are on reduced monitoring under subpart L and were not required to monitor during the specified period. If you did not monitor
                                       during the specified period, you must base your eligibility on compliance samples taken during the 12 months preceding the specified period.

                                         c. Implementation. All systems                                          monitoring, study plan for system                               requirements for the IDSE plan depend
                                       subject to the IDSE requirement under                                     specific study) or 40/30 certification to                       on the IDSE approach that the system
                                       this final rule (except those covered by                                  the State or primacy agency. IDSE plans                         selects and are listed in Tables IV.F–1
                                       the very small system waiver) must                                        and 40/30 certifications must be                                and IV.F–3.
                                       prepare and submit an IDSE plan                                           submitted according to the schedule
                                       (monitoring plan for standard                                             described in section IV.E and IV.M. The

                                                                                               TABLE IV.F–3.—IDSE MONITORING PLAN REQUIREMENTS
                                          IDSE data collection alternative                                                                                  IDSE plan requirements

                                       Standard Monitoring ........................              • Schematic of the distribution system (including distribution system entry points and their sources, and
                                                                                                   storage facilities), with notes indicating locations and dates of all projected standard monitoring, and all
                                                                                                   projected subpart L compliance monitoring.
                                                                                                 • Justification for all standard monitoring locations selected and a summary of data relied on to select
                                                                                                   those locations.
                                                                                                 • Population served and system type (subpart H or ground water).
                                       System Specific Study:
                                       Hydraulic Model ..............................            Hydraulic models must meet the following criteria:
                                                                                                 • Extended period simulation hydraulic model.
                                                                                                 • Simulate 24 hour variation in demand and show a consistently repeating 24 hour pattern of residence
                                                                                                 • Represent 75% of pipe volume; 50% of pipe length; all pressure zones; all 12-inch diameter and larger
                                                                                                   pipes; all 8-inch and larger pipes that connect pressure zones, influence zones from different sources,
                                                                                                   storage facilities, major demand areas, pumps, and control valves, or are known or expected to be sig-
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                                                                                                   nificant conveyors of water; all pipes 6 inches and larger that connect remote areas of a distribution sys-
                                                                                                   tem to the main portion of the system; all storage facilities with standard operations represented in the
                                                                                                   model; all active pump stations with controls represented in the model; and all active control valves.

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                             421

                                                                        TABLE IV.F–3.—IDSE MONITORING PLAN REQUIREMENTS—Continued
                                          IDSE data collection alternative                                                        IDSE plan requirements

                                                                                   • The model must be calibrated, or have calibration plans, for the current configuration of the distribution
                                                                                     system during the period of high TTHM formation potential. All storage facilities must be evaluated as
                                                                                     part of the calibration process.
                                                                                   • All required calibration must be completed no later than 12 months after plan submission.
                                                                                   Submission must include:
                                                                                   • Tabular or spreadsheet data demonstrating percent of total pipe volume and pipe length represented in
                                                                                     the model, broken out by pipe diameter, and all required model elements.
                                                                                   • A description of all calibration activities undertaken, and if calibration is complete, a graph of predicted
                                                                                     tank levels versus measured tank levels for the storage facility with the highest residence time in each
                                                                                     pressure zone, and a time series graph of the residence time at the longest residence time storage facil-
                                                                                     ity in the distribution system showing the predictions for the entire simulation period (i.e., from time zero
                                                                                     until the time it takes for the model to reach a consistently repeating pattern of residence time).
                                                                                   • Model output showing preliminary 24 hour average residence time predictions throughout the distribution
                                                                                   • Timing and number of samples planned for at least one round of TTHM and HAA5 monitoring at a num-
                                                                                     ber of locations no less than would be required for the system under standard monitoring in § 141.601
                                                                                     during the historical month of high TTHM. These samples must be taken at locations other than existing
                                                                                     subpart L compliance monitoring locations.
                                                                                   • Description of how all requirements will be completed no later than 12 months after submission of the
                                                                                     system specific study plan.
                                                                                   • Schematic of the distribution system (including distribution system entry points and their sources, and
                                                                                     storage facilities), with notes indicating the locations and dates of all completed system specific study
                                                                                     monitoring (if calibration is complete) and all subpart L compliance monitoring.
                                                                                   • Population served and system type (subpart H or ground water).
                                                                                   • If the model submitted does not fully meet the requirements, the system must correct the deficiencies
                                                                                     and respond to State inquiries on a schedule the State approves, or conduct standard monitoring.
                                       System Specific Study:
                                       Existing Monitoring Results ............    Existing monitoring results must meet the following criteria:
                                                                                   • TTHM and HAA5 results must be based on samples collected and analyzed in accordance with
                                                                                     § 141.131. Samples must be collected within five years of the study plan submission date.
                                                                                   • The sampling locations and frequency must meet the requirements identified in Table IV.F–4. Each loca-
                                                                                     tion must be sampled once during the peak historical month for TTHM levels or HAA5 levels or the
                                                                                     month of warmest water temperature for every 12 months of data submitted for that location. Monitoring
                                                                                     results must include all subpart L compliance monitoring results plus additional monitoring results as
                                                                                     necessary to meet minimum sample requirements.
                                                                                   Submission must include:
                                                                                   • Previously collected monitoring results
                                                                                   • Certification that the reported monitoring results include all compliance and non-compliance results gen-
                                                                                     erated during the time period beginning with the first reported result and ending with the most recent
                                                                                     subpart L results.
                                                                                   • Certification that the samples were representative of the entire distribution system and that treatment
                                                                                     and distribution system have not changed significantly since the samples were collected.
                                                                                   • Schematic of the distribution system (including distribution system entry points and their sources, and
                                                                                     storage facilities), with notes indicating the locations and dates of all completed or planned system spe-
                                                                                     cific study monitoring.
                                                                                   • Population served and system type (subpart H or ground water).
                                                                                   • If a system submits previously collected data that fully meet the number of samples required for IDSE
                                                                                     monitoring in Table IV.F–4 and some of the data are rejected due to not meeting the additional require-
                                                                                     ments, the system must either conduct additional monitoring to replace rejected data on a schedule the
                                                                                     State approves, or conduct standard monitoring.

                                                                     TABLE IV.F–4.—SSS EXISTING MONITORING DATA SAMPLE REQUIREMENTS.
                                                                                                                                                     Number of          Number of samples
                                                                     System type                                     Population size category       monitoring lo-
                                                                                                                                                      cations           TTHM           HAA5

                                          Subpart H:

                                                                                                                                             <500                 3              3              3

                                                                                                                                        500–3,300                 3              9              9

                                                                                                                                   3,301–9,999                    6            36              36
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                                                                                                                                10,000–49,999                    12            72              72

                                                                                                                               50,000–249,999                    24            144            144

                                                                                                                              250,000–999,999                    36            216            216

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                                                              TABLE IV.F–4.—SSS EXISTING MONITORING DATA SAMPLE REQUIREMENTS.—Continued
                                                                                                                                                        Number of          Number of samples
                                                                       System type                                     Population size category        monitoring lo-
                                                                                                                                                         cations           TTHM         HAA5

                                                                                                                              1,000,000–4,999,999                   48            288          288

                                                                                                                                       ≥ 5,000,000                  60            360          360

                                          Ground Water:                                                                                         <500                 3              3            3

                                                                                                                                           500–9,999                 3              9            9

                                                                                                                                   10,000–99,999                    12             48           48

                                                                                                                                 100,000–499,999                    18             72           72

                                                                                                                                           ≥ 500,000                24             96           96

                                         The State or primacy agency will                        the IDSE plan approved by the State or                   monitoring plan submission may submit
                                       approve the IDSE plan or 40/30                            primacy agency according to the                          a combined monitoring plan and report
                                       certification, or request modifications. If               schedule described in section IV.E.                      on the required schedule for IDSE plan
                                       the State or primacy agency has not                         All systems completing standard                        submissions. The requirements for the
                                       taken action by the date specified in                     monitoring or a system specific study                    IDSE report are listed in Table IV.F–5.
                                       section IV.E or has not notified the                      must submit a report to the State or                     Some of these reporting requirements
                                       system that review is not yet complete,                   primacy agency according to the                          have changed from the proposal to
                                       systems may consider their submissions                    schedule described in section IV.E.                      reduce reporting and paperwork burden
                                       to be approved. Systems must                              Systems that have completed their                        on systems.
                                       implement the IDSE option described in                    system specific study at the time of

                                                                                            TABLE IV.F–5.—IDSE REPORT REQUIREMENTS
                                          IDSE data collection alternative                                                          IDSE report requirements

                                       Standard Monitoring ........................   • All subpart L compliance monitoring and standard monitoring TTHM and HAA5 analytical results in a
                                                                                        tabular format acceptable to the State.
                                                                                      • If changed from the monitoring plan, a schematic of the distribution system, population served, and sys-
                                                                                        tem type.
                                                                                      • An explanation of any deviations from the approved monitoring plan.
                                                                                      • Recommendations and justifications for subpart V compliance monitoring locations and timing.
                                       System Specific Study ....................     • All subpart L compliance monitoring and all system specific study monitoring TTHM and HAA5 analytical
                                                                                        results conducted during the period of the system specific study in a tabular or spreadsheet form accept-
                                                                                        able to the State.
                                                                                      • If changed from the study plan, a schematic of the distribution system, population served, and system
                                                                                      • If using the modeling provision, include final information for required plan submissions and a 24-hour
                                                                                        time series graph of residence time for each subpart V compliance monitoring location selected.
                                                                                      • An explanation of any deviations from the original study plan.
                                                                                      • All analytical and modeling results used to select subpart V compliance monitoring locations that show
                                                                                        that the system specific study characterized TTHM and HAA5 levels throughout the entire distribution
                                                                                      • Recommendations and justifications for subpart V compliance monitoring locations and timing.

                                         All systems must prepare Stage 2                        today’s final rule, and in section IV.G.                 agency has not taken action by the date
                                       compliance monitoring                                     Generally, a system must recommend                       specified in section IV.E or has not
                                       recommendations. All IDSE reports                         locations with the highest LRAAs unless                  notified the system that review is not
                                       must include recommendations for                          it provides a rationale (such as ensuring                yet complete, systems may consider
                                       Stage 2 compliance monitoring                             geographical coverage of the                             their submission to be approved and
                                       locations and sampling schedule.                          distribution system instead of clustering                prepare to begin Stage 2 compliance
                                       Systems submitting a 40/30 certification                  all sites in a particular section of the                 monitoring.
                                       must include their Stage 2 compliance                     distribution system) for selecting other                   EPA has developed the Initial
                                       monitoring recommendations in their                       locations. In evaluating possible Stage 2                Distribution System Evaluation
                                       Stage 2 (Subpart V) monitoring plan                       compliance monitoring locations,                         Guidance Manual for the Final Stage 2
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                                       unless the State requests Subpart V site                  systems must consider both Stage 1                       Disinfectants and Disinfection
                                       recommendations as part of the 40/30                      DBPR compliance data and IDSE data.                      Byproducts Rule (USEPA 2006) to assist
                                       certification. The number of sampling                        The State or primacy agency will                      systems with implementing each of
                                       locations and the criteria for their                      approve the IDSE report or request                       these requirements. This guidance may
                                       selection are described in § 141.605 of                   modifications. If the State or primacy                   be requested from EPA’s Safe Drinking

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                                       Water Hotline, which may be contacted                   compliance data, identify high DBP                     small systems (serving <500) at both
                                       as described under FOR FURTHER                          locations. Monitoring at additional sites              average residence time and maximum
                                       INFORMATION CONTACT in the beginning                    increases the chance of finding sites                  residence time locations are lower than
                                       of this notice. This guidance manual is                 with high DBP levels and targets both                  levels at both of those locations in larger
                                       also available on the EPA Web site at                   DBPs that degrade and DBPs that form                   systems, and the change in residual
                                       http://www.epa.gov/safewater/stage2/                    as residence time increases in the                     concentration between those two
                                       index.html.                                             distribution system. EPA believes that                 locations is smaller in very small
                                                                                               the required number of standard                        systems compared to larger sized
                                       2. Background and Analysis
                                                                                               monitoring locations plus Stage 1                      systems. The magnitude of the
                                          In the Stage 2 DBPR proposal                         monitoring results will provide an                     reduction in residual concentration
                                       (USEPA, 2003a), EPA proposed                            adequate characterization of DBP levels                gives an indication of how much
                                       requirements for systems to complete an                 throughout the distribution system at a                disinfectant has reacted to form DBPs,
                                       IDSE. The Agency based its proposal                     reasonable cost. By revising Stage 2                   including TTHM and HAA5. The
                                       upon the Stage 2 M–DBP Advisory                         compliance monitoring plans to target                  smaller reduction in disinfectant
                                       Committee recommendations in the                        locations with high DBPs, systems will                 concentration between average
                                       Agreement in Principle. The Advisory                    be required to take steps to address high              residence time and maximum residence
                                       Committee believed and EPA concurs                      DBP levels at locations that might                     time in very small systems compared to
                                       that maintaining Stage 1 DBPR                           otherwise have gone undetected.                        larger systems indicates that DBP
                                       monitoring sites for the Stage 2 DBPR                      The Advisory Committee                              formation potential is probably lower in
                                       would not accomplish the risk-targeting                 recommended that an IDSE be                            very small systems compared to larger
                                       objective of minimizing high DBP levels                 performed by all community water                       systems, and the likelihood for
                                       and providing consistent and equitable                  systems, unless the system had                         significant DBP variation within the
                                       protection across the distribution                      sufficiently low DBP levels or is a very               distribution system of very small
                                       system. Most of these requirements have                 small system with a simple distribution                systems is low if the distribution system
                                       not changed from the proposed rule.                     system. EPA believes that large                        is small and not complex. However,
                                          The data collection requirements of                  nontransient noncommunity water                        there may be some small systems with
                                       the IDSE are designed to find both high                 systems (NTNCWS) (those serving at                     extended or complex distribution
                                       TTHM and high HAA5 sites (see section                   least 10,000 people) also have                         systems that should be studied further
                                       IV.G for IDSE monitoring requirements).                 distribution systems that require further              to determine new sampling locations.
                                       High TTHM and HAA5 concentrations                       evaluation to determine the locations                  For this reason, States or primacy
                                       often occur at different locations in the               most representative of high DBP levels                 agencies can require any particular very
                                       distribution system. The Stage 1 DBPR                   and proposed that they be required to
                                       monitoring sites identified as the                                                                             small system to conduct an IDSE. Very
                                                                                               conduct an IDSE. Therefore, large                      small systems subject to the Stage 2
                                       maximum location are selected                           NTNCWS and all community water
                                       according to residence time. HAAs can                                                                          DBPR that do not have a Stage 1
                                                                                               systems are required to comply with                    compliance monitoring location may
                                       degrade in the distribution system in the               IDSE requirements under today’s final
                                       absence of sufficient disinfectant                                                                             monitor in accordance with the Stage 1
                                                                                               rule, unless they submit a 40/30                       DBPR provisions to be eligible for this
                                       residual (Baribeau et al. 2000).                        certification or they are covered by the
                                       Consequently, residence time is not an                                                                         waiver.
                                                                                               very small system waiver provisions.
                                       ideal criterion for identifying high                       b. Very small system waivers. Systems                  c. 40/30 certifications. Systems that
                                       HAA5 sites. In addition, maximum                        serving fewer than 500 people that have                certify to their State or primacy agency
                                       residence time locations that are                       taken samples under the Stage 1 DBPR                   that all compliance samples taken
                                       associated with high TTHM levels may                    will receive a very small system waiver.               during eight consecutive calendar
                                       not be constant due to daily or seasonal                EPA proposed and the Advisory                          quarters prior to the start of the IDSE
                                       changes in demand. The analysis of                      Committee recommended a very small                     were ≤0.040 mg/L TTHM and ≤0.030
                                       maximum residence time completed for                    system waiver following a State                        mg/L HAA5 are not required to collect
                                       the selection of Stage 1 monitoring sites               determination that the existing Stage 1                additional DBP monitoring data under
                                       may not have been capable of detecting                  compliance monitoring location                         the IDSE requirements as long as the
                                       these variations. The Information                       adequately characterizes both high                     system has no TTHM or HAA5
                                       Collection Rule data show that over 60                  TTHM and high HAA5 for the                             monitoring violations. These criteria
                                       percent of the highest HAA5 LRAAs and                   distribution system because many very                  were developed because both EPA and
                                       50 percent of the highest TTHM LRAAs                    small systems have small or simple                     the AdvisoryCommittee determined that
                                       were found at sampling locations in the                 distribution systems. The final rule                   these systems most likely would not
                                       distribution system other than the                      grants the very small system waiver to                 have DBP levels that exceed the MCLs.
                                       maximum residence time compliance                       all systems serving fewer than 500 that                Systems must have qualifying TTHM
                                       monitoring location (USEPA 2003a).                      have Stage 1 DBPR data. This provision                 and HAA5 data for eight consecutive
                                       Therefore, the method and assumptions                   was changed from the proposal to reflect               calendar quarters according to the
                                       used to select the Information Collection               that most very small systems that                      schedule in Table IV.F–2 to be eligible
                                       Rule monitoring sites and the Stage 1                   sample under the Stage 1 DBPR have                     for this option. Systems on reduced
                                       DBPR compliance monitoring sites may                    sampling locations that are                            monitoring that did not monitor during
                                       not reliably capture high DBP levels for                representative of both high TTHM and                   the specified time period may use data
                                       Stage 2 DBPR compliance monitoring                      high HAA5 because most very small                      from the prior year to meet the 40/30
                                       sites.                                                  systems have small and simple                          certification criteria. Systems that have
                                          a. Standard monitoring. The Advisory                 distribution systems. In addition, many                not previously conducted Stage 1 DBPR
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                                       Committee recommended that systems                      very small systems are ground water                    compliance monitoring may begin such
                                       sample throughout the distribution                      systems that typically have stable DBP                 monitoring to collect the data necessary
                                       system at twice the number of locations                 levels that tend to be lower than surface              to qualify for 40/30 certification. The
                                       as required under Stage 1 and, using                    water DBP levels. NRWA survey data                     certification and data supporting it must
                                       these results in addition to Stage 1                    show that free chlorine residual in very               be available to the public upon request.

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                                       424               Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                          The qualifying time period for the 40/               compliance monitoring as part of the                   requirements reflect the fact that the
                                       30 certification has changed from the                   40/30 certification. This provision was                purpose of the model is to predict water
                                       proposed rule.                                          included to facilitate primacy agency                  age. ICR data show that HAA5 data do
                                          Under the proposed rule, the rule                    review of 40/30 certifications; the                    not necessarily correlate well with water
                                       language identified a specific two year                 additional information is only required                age (USEPA 2003a). Because the
                                       window with start and end dates. In                     if requested by the primacy agency.                    purpose of the IDSE is to locate
                                       today’s final rule, the qualifying time                    d. System specific studies. Advisory                representative high locations for both
                                       period has been changed to ‘‘eight                      Committee members recognized that                      TTHM and HAA5, one round of
                                       consecutive calendar quarters of subpart                some systems have detailed knowledge                   monitoring must be completed at
                                       L compliance monitoring results                         of their distribution systems by way of                potential Stage 2 compliance monitoring
                                       beginning no earlier than * * *’’ (see                  ongoing hydraulic modeling and/or                      locations to determine appropriate
                                       Table IV.F–2). This change was made so                  existing widespread monitoring plans                   HAA5 monitoring locations during the
                                       that systems that have made a treatment                 (beyond that required for compliance                   historical high month of TTHM
                                       change within the two years prior to                    monitoring) that would provide                         concentrations. The number of locations
                                       rule promulgation and have collected                    equivalent or superior monitoring site                 must be no less than would be required
                                       initial data that meet the 40/30 criteria               selection information compared to                      under standard monitoring.
                                       might have the opportunity to collect                   standard monitoring. Therefore, the                       Preliminary average residence time
                                       eight consecutive quarters of qualifying                Advisory Committee recommended that                    data are required as a part of the study
                                       data and apply for a 40/30 certification.               such systems be allowed to determine                   plan for systems to demonstrate that
                                       This schedule change also allows                        new monitoring sites using system-                     their distribution system hydraulic
                                       systems that have not previously                        specific data such as hydraulic model                  model is able to produce results for
                                       monitored under Stage 1 an opportunity                  results or existing monitoring data; this              water age throughout the distribution
                                       to qualify for a 40/30 certification.                   provision remains in the final rule. In                system, even though calibration may not
                                          Under the proposed Stage 2 DBPR,                     the proposed rule, the only specification              be complete. Systems also need to
                                       systems that missed the deadline for                    for SSSs was to identify monitoring sites              describe their plans to complete the
                                       submitting a 40/30 certification would                  that would be equivalent or superior to                modeling requirements within 12
                                       be required to conduct either standard                  those identified under Standard                        months of submitting the study plan.
                                       monitoring or a system specific study                   Monitoring. The final rule includes                    These last two requirements were
                                       even if the system otherwise qualified                  more specific requirements on how                      developed so that States can be assured
                                       for the 40/30 certification. Under                      these studies should be completed. The                 that systems have the technical capacity
                                       today’s final rule, systems that do not                 requirements in the final rule were                    to complete their modeling
                                       make any submission by the IDSE plan                    developed to be consistent with the                    requirements by the IDSE report
                                       submission deadline will still receive a                proposal, yet more specific to help                    deadline. If systems cannot demonstrate
                                       violation, but may submit a late 40/30                  systems better understand expectations                 that they are in a position to complete
                                       certification if their data meet the                    under this provision and lessen the                    the modeling requirements according to
                                       requirements. This change was made so                   chances of a study plan not being                      the required schedule, they will be
                                       that systems and primacy agencies do                    approved.                                              required to complete standard
                                       not spend time preparing and reviewing                     The new modeling requirements were                  monitoring.
                                       standard monitoring plans and IDSE                      developed to reflect that hydraulic                       All new modeling requirements were
                                       reports for systems with a low                          models can identify representative high                added to help systems demonstrate how
                                       likelihood of finding high TTHM and                     TTHM monitoring locations by                           their model will fulfill the purpose and
                                       HAA5 levels.                                            predicting hydraulic residence time in                 requirements of the IDSE and to assist
                                          The reporting requirements for this                  the distribution system. Water age has                 primacy agencies with approval
                                       provision have been reduced from the                    been found to correlate with TTHM                      determinations. The associated
                                       requirements in the proposed                            formation in the distribution system.                  reporting requirements were developed
                                       rulemaking. In the proposal, systems                    Consequently, for this system specific                 to balance the needs of systems to
                                       qualifying for the 40/30 certification                  study approach, hydraulic residence                    demonstrate that they have fulfilled the
                                       were required to submit all qualifying                  time predicted by the model is used as                 requirements and the needs of primacy
                                       data and provide recommendations for                    a surrogate for TTHM formation to                      agency reviewers to be able to
                                       Stage 2 compliance monitoring                           locate appropriate Stage 2 compliance                  understand the work completed by the
                                       locations. The final rule requires                      monitoring locations. To predict                       system.
                                       systems to submit a certification that                  hydraulic residence time in the                           EPA has specified new requirements
                                       their data meet all the requirements of                 distribution system, the model must                    for systems complete an SSS using
                                       the 40/30 certification and to include                  represent most of the distribution                     existing monitoring data to help systems
                                       their Stage 2 compliance monitoring                     system and must have been calibrated                   understand the extent of historical data
                                       recommendations in their Stage 2                        recently and appropriately to reflect                  that would meet the requirements of the
                                       monitoring plan. These changes were                     water age in the distribution system.                  IDSE. The number of required sample
                                       made to reduce the reporting burden on                  Requirements to reflect this are in                    locations and samples are consistent
                                       systems that qualify for the 40/30                      today’s rule. All storage facilities must              with sampling requirements under
                                       certification and to maintain                           be evaluated for the calibration, and                  standard monitoring and the
                                       consistency with monitoring plan                        systems using this option must submit                  recommendations made by the Advisory
                                       requirements under the Stage 1 DBPR.                    a graph of predicted tank levels versus                Committee. The Advisory Committee
                                       This approach also gives systems more                   measured tank levels for the storage                   recommended that systems complete an
                                       time to select appropriate monitoring                   facility with the highest residence time               IDSE sample at twice the number of
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                                       sites for Stage 2 compliance monitoring.                in each pressure zone. These calibration               sites required by the Stage 1 DBPR in
                                       The State or primacy agency may                         requirements are focused on storage                    addition to Stage 1 DBPR sampling.
                                       request systems to submit the data, a                   facilities because they are the largest                Because the number of required Stage 1
                                       distribution system schematic, and/or                   controlling factor for water age in the                DBPR monitoring locations varies
                                       recommendations for Stage 2                             distribution system. The calibration                   within each population category under

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                                       the Stage 1 plant-based monitoring                      existing monitoring results were taken                    In addition to addressing the very
                                       approach (since systems have different                  during the earliest eligible dates. Again,             small system waivers, commenters
                                       numbers of plants), EPA used the                        these clarifications were made so that                 suggested that different criteria should
                                       number of required Standard                             systems could better understand the                    be used for the 40/30 certification, such
                                       Monitoring locations plus the number of                 extent of data necessary for a monitoring              as higher minimum DBP levels, cut-offs
                                       Stage 2 compliance monitoring                           plan to be deemed acceptable and be                    of 40/30 as LRAAs or RAAs rather than
                                       locations to develop minimum                            confident that efforts to complete an                  single sample maximums, or State or
                                       requirements for the use of existing                    SSS would be found acceptable to the                   primacy agency discretion on which
                                       monitoring data for the SSS. The                        State or primacy agency.                               systems should qualify for 40/30
                                       number of required locations and                          e. Distribution System Schematics.                   certification. There was no consensus
                                       samples are shown in Table IV.F–4.                      EPA has considered security concerns                   among the commenters on what changes
                                       Systems will use their Stage 1                          that may result from the requirement for               should be made to the proposal for the
                                       monitoring results plus additional non-                 systems to submit a distribution system                40/30 certification requirements. EPA
                                       compliance or operational samples to                    schematic as part of their IDSE plan.                  did not change the requirements for the
                                       fulfill these requirements. Small                       EPA believes that the final rule strikes               40/30 certification eligibility because
                                       systems with many plants may have                       an appropriate balance between security                the recommended alternatives were not
                                       been collecting a disproportionate                      concerns and the need for States and                   technically superior to the requirements
                                       number of samples under the Stage 1                     primacy agencies to be able to review                  of the proposed rule. Implementation of
                                       DBPR compared to the population based                   IDSE plans. EPA has developed                          40/30 criteria using an LRAA or RAA
                                       monitoring requirements presented in                    guidance for systems on how to submit                  would result in reduced public health
                                       today’s rule and may have sufficient                    a distribution system schematic that                   protection from the rule by allowing
                                       historical data to characterize the entire              does not include sensitive information.                higher DBP levels to go undetected. EPA
                                       distribution system. These requirements                 3. Summary of Major Comments                           did change the eligibility dates and
                                       allow those systems to submit an SSS                                                                           reporting requirements for the 40/30
                                       based on existing Stage 1 monitoring                       The Agency received significant                     certification to reduce the burden on the
                                       results, and they also accommodate                      comments on the following issues                       system. Under today’s final rule, States
                                       systems that have been completing                       related to the proposed IDSE                           or primacy agencies can request TTHM
                                       additional monitoring throughout the                    requirements: Waiver limitations, and                  and HAA5 data as desired for a more in-
                                       distribution system.                                    State or primacy agency review of IDSE                 depth review of a system’s
                                          The requirement to sample during the                 plans.                                                 qualifications.
                                       historical month of high TTHM, high                        In the proposed rule, EPA requested                    Many commenters expressed concern
                                       HAA5, or warmest water temperature                      comment on what the appropriate                        over the implementation schedule for
                                       during each year for which data were                    criteria should be for States or primacy               the IDSE. Commenters were especially
                                       collected was added to maintain                         agencies to grant very small system                    concerned that IDSE plans would be
                                       consistency with the standard                           waivers. Commenters responded with a                   developed and implemented prior to
                                       monitoring requirements where each                      wide range of suggestions including                    State primacy, and once States receive
                                       location must be sampled one time                       support for the proposal as written,                   primacy, they might not support the
                                       during the peak historical month.                       different population cut-offs, State or                IDSE plan and would reject the results
                                       Samples that qualify for this SSS must                  primacy agency discretion on what                      of the completed IDSE. To address this
                                       have been collected within five years of                system size should qualify for the                     issue, commenters requested the
                                       the study plan submission date and                      waiver, and alternative waiver criteria                opportunity for States to review the
                                       must reflect the current configuration of               such as pipe length or number of                       IDSE plans prior to systems completing
                                       treatment and the distribution system.                  booster stations. There was no                         their IDSEs. In today’s rule EPA has
                                       Five years was selected as a cut off for                consensus among the commenters on                      modified the compliance schedule for
                                       eligible data so that all data submitted                what changes should be made to the                     the Stage 2 DBPR so that systems have
                                       would be reasonably representative of                   proposal for the very small system                     the opportunity to complete their IDSE
                                       current source water conditions and                     waiver requirements. EPA did not                       plan and have it reviewed by the
                                       DBP formation within the distribution                   change the population cutoff for the                   primacy agency prior to completing the
                                       system. Data that are older may not                     very small system waiver because                       IDSE to address the concern that States
                                       reflect current DBP formation potential                 analysis of NRWA survey data also                      or primacy agencies may reject the
                                       in the distribution system. Five years                  showed that systems serving fewer than                 results of the completed IDSE. The
                                       prior to the submission of the study                    500 had different residence times and                  changes to the compliance schedule are
                                       plan also correlates with the signing of                lower free chlorine residual                           discussed further in section IV.E.
                                       the Agreement in Principle where the                    concentrations compared to other
                                                                                               population categories, indicating that                 G. Monitoring Requirements and
                                       Advisory Committee made the
                                                                                               larger systems have different DBP                      Compliance Determination for TTHM
                                       recommendation for this provision.
                                                                                               formation characteristics compared to                  and HAA5 MCLs
                                       Systems interested in using this
                                       provision would have started eligible                   very small systems. Some of the                          EPA is finalizing monitoring
                                       monitoring after the agreement was                      suggested changes for very small system                requirements under a population-based
                                       signed.                                                 waiver criteria may require data that are              approach described in this section. EPA
                                          Systems that submit existing                         not readily available to systems (such as              believes the population-based approach
                                       monitoring data must submit all Stage 1                 pipe length in service) and for which                  will provide more representative high
                                       sample results from the beginning of the                there were no specific criteria proposed               DBP concentrations throughout
                                       SSS to the time when the SSS plan is                    or recommended by the commenters.                      distribution systems than would plant-
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                                       submitted. The purpose of this                          Implementation of subjective very small                based monitoring, is equitable, and will
                                       requirement is to demonstrate that there                system waiver criteria would result in                 simplify implementation for both States
                                       have been no significant changes in                     reduced public health protection from                  and systems. For these reasons, EPA
                                       source water quality since the first                    the rule by allowing higher DBP levels                 believes this approach is more
                                       samples were collected, especially if all               to go undetected.                                      appropriate than the proposed plant-

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                                       based monitoring. Detailed discussion                           based approach, monitoring                                             must collect samples during the peak
                                       of the two approaches is presented in                           requirements are based solely on the                                   historical month for DBP levels or water
                                       the preamble of the proposed rule                               retail population served and the type of                               temperature; this will determine their
                                       (USEPA 2003a) and EA for today’s rule                           source water used and not influenced by                                monitoring schedule. Table IV.G–1
                                       (USEPA 2005a).                                                  the number of treatment plants or entry                                contains the IDSE monitoring
                                       1. Today’s Rule                                                 points in the distribution system as in                                frequencies and locations for all source
                                                                                                       previous rules (i.e., TTHM Rule (USEPA                                 water and size category systems. Section
                                          Today’s rule establishes TTHM and
                                                                                                       1979) and Stage 1 DBPR (USEPA                                          IV.F identifies other approaches by
                                       HAA5 monitoring requirements for all
                                       systems based on a population-based                             1998a)).                                                               which systems can meet IDSE
                                       monitoring approach instead of a plant-                           a. IDSE Monitoring. All systems                                      requirements.
                                       based approach. Under the population-                           conducting IDSE standard monitoring

                                                                              TABLE IV.G–1.—IDSE MONITORING FREQUENCIES AND LOCATIONS
                                                                                                                                                              Distribution system monitoring locations 1
                                        Source water                                              Monitoring periods and
                                                          Population size category                                                           Total per                                  Average
                                            type                                                  frequency of sampling                      monitoring        Near entry              residence            High TTHM    High HAA5
                                                                                                                                                                 points                                      locations    locations
                                                                                                                                              period                                      time

                                       Subpart H
                                                         <500 consecutive sys-                  one (during peak histor-                                 2                      1    ....................            1
                                                           tems.                                   ical month) 2.
                                                         <500 non-consecutive                   ..........................................                2   ....................   ....................            1                     1

                                                         500–3,300 non-consecu-                 four (every 90 days) ........                             2                    1     ....................            1   ....................
                                                           tive systems.
                                                         500–3,300 consecutive                  ..........................................               2    ....................   ....................            1                     1

                                                         3,301–9,999 .....................      ..........................................                4   ....................                    1              2                   1
                                                         10,000–49,999 .................        six (every 60 days) ..........                            8                     1                     2              3                   2
                                                         50,000–249,999 ...............         ..........................................               16                     3                     4              5                   4
                                                         250,000–999,999 .............          ..........................................               24                     4                     6              8                   6
                                                         1,000,000–4,999,999 .......            ..........................................               32                     6                     8             10                   8
                                                         ≥5,000,000 .......................     ..........................................               40                     8                    10             12                  10

                                                         <500 consecutive sys-                  one (during peak histor-                                 2                      1    ....................            1   ....................
                                                           tems.                                  ical month) 2.

                                                         <500 non-consecutive                   ..........................................                2   ....................   ....................            1                     1
                                                         500–9,999 ........................     four (every 90 days) ........                             2   ....................   ....................            1                     1
                                                         10,000–99,999 .................        ..........................................                6                     1                      1             2                     2
                                                         100,000–499,999 .............          ..........................................                8                     1                      1             3                     3
                                                         ≥500,000 ..........................    ..........................................               12                     2                      2             4                     4
                                          1A   dual sample set (i.e., a TTHM and an HAA5 sample) must be taken at each monitoring location during each monitoring period.
                                          2 The  peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water temperature.

                                          b. Routine Stage 2 Compliance                                additional monitoring locations, if                                    levels. Systems may also recommend
                                       Monitoring. For all systems conducting                          required by the transition from plant-                                 locations with lower levels of DBPs that
                                       either standard monitoring or a system                          based monitoring to population-based                                   would not be picked up by the protocol
                                       specific study, initial Stage 2                                 monitoring.                                                            if they provide a rationale for the
                                       compliance monitoring locations are                               Systems recommend Stage 2                                            recommendation. Examples of
                                       based on the system’s IDSE results,                             monitoring locations generally by                                      rationales include ensuring better
                                       together with an analysis of a system’s                         arraying results of IDSE standard                                      distribution system or population
                                       Stage 1 DBPR compliance monitoring                              monitoring (or system specific study                                   coverage (not having all locations in the
                                       results. Systems receiving 40/30                                results) and Stage 1 compliance                                        same area) or maintaining existing
                                       certification or a very small system                            monitoring by monitoring location (from                                locations with DBP levels that are nearly
                                       waiver, and nontransient                                        highest to lowest LRAA for both TTHM                                   as high as those that would otherwise be
                                       noncommunity water systems serving                              and HAA5). Using the protocol in                                       selected. The State or primacy agency
                                       <10,000 not required to conduct an                              § 141.605(c) of today’s rule, systems                                  will review these recommendations as
                                       IDSE, base Stage 2 initial compliance                           then select the required number of                                     part of the review of the IDSE report
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                                       monitoring locations on the system’s                            locations. Larger systems include                                      submitted by systems that conducted
                                       Stage 1 DBPR compliance monitoring                              existing Stage 1 monitoring locations in                               standard monitoring or a system specific
                                       results. Some of these systems may also                         order to be able to have historical                                    study.
                                       need an evaluation of distribution                              continuity for evaluating how changes                                     Table IV.G–2 contains the routine
                                       system characteristics to identify                              in operations or treatment affect DBP                                  Stage 2 TTHM and HAA5 compliance

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                                                      427

                                       monitoring requirements for all systems                       report (those receiving a 40/30                                   period’’ column at current Stage 1
                                       (both non-consecutive and consecutive                         certification or very small system waiver                         compliance monitoring locations, unless
                                       systems), as well as the protocol for                         and nontransient noncommunity water                               the State or primacy agency specifically
                                       Stage 2 compliance monitoring location                        systems serving <10,000) must conduct                             directs otherwise. All systems are then
                                       selection in the IDSE report. Systems                         Stage 2 compliance monitoring as                                  required to maintain and follow a Stage
                                       that do not have to submit an IDSE                            indicated in the ‘‘Total per monitoring                           2 compliance monitoring plan.

                                                                 TABLE IV.G–2. ROUTINE COMPLIANCE MONITORING FREQUENCIES AND LOCATIONS
                                                                                                                                                                      Distribution system monitoring location
                                             Source water type               Population size category                   Monitoring frequency1                  Total per      Highest        Highest       Subpart L
                                                                                                                                                               monitoring   TTHM loca-      HAA5 loca-    compliance
                                                                                                                                                                period2        tions          tions        locations

                                       Subpart H:
                                                                         <500 ..................................    per   year .............................            2               1             1   ....................
                                                                         500–3,300 .........................        per   quarter ........................              2               1             1   ....................
                                                                         3,301–9,999 ......................         per   quarter ........................              2               1             1   ....................
                                                                         10,000–49,999 ..................           per   quarter ........................              4               2             1                     1
                                                                         50,000–249,999 ................            per   quarter ........................              8               3             3                     2
                                                                         250,000–999,999 ..............             per   quarter ........................             12               5             4                     3
                                                                         1,000,000–4,999,999 ........               per   quarter ........................             16               6             6                     4
                                                                         ≥ 5,000,000 .......................        per   quarter ........................             20               8             7                     5
                                       Ground water:
                                                                         <500 ..................................    per   year .............................            2               1             1   ....................
                                                                         500–9,999 .........................        per   year .............................            2               1             1   ....................
                                                                         10,000–99,999 ..................           per   quarter ........................              4               2             1                     1
                                                                         100,000–499,999 ..............             per   quarter ........................              6               3             2                     1
                                                                         ≥ 500,000 ..........................       per   quarter ........................              8               3             3                     2
                                          1 All
                                              systems must monitor during month of highest DBP concentrations.
                                          2 Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for subpart H systems serving
                                       500–3,300. Systems on annual monitoring and subpart H systems serving 500–3,300 are required to take individual TTHM and HAA5 samples
                                       (instead of a dual sample set) at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sam-
                                       ple set per monitoring period is needed if highest TTHM and HAA5 concentrations occur at the same location, and month, if monitored annually).

                                          Today’s rule provides States the                           and chloramines. States may use the                               0.040 mg/L for TTHM or 0.030 mg/L for
                                       flexibility to specify alternative Stage 2                    provisions of § 141.134(c) to modify                              HAA5 or if the source water annual
                                       compliance monitoring requirements                            reporting requirements. For example,                              average TOC level, before any treatment,
                                       (but not alternative IDSE monitoring                          the State may require that only the                               exceeds 4.0 mg/L at any of the system’s
                                       requirements) for multiple consecutive                        consecutive system distribution system                            treatment plants treating surface water
                                       systems in a combined distribution                            point-of-entry disinfectant                                       or ground water under the direct
                                       system. As a minimum under such an                            concentration be reported to                                      influence of surface water, the system
                                       approach, each consecutive system must                        demonstrate MRDL compliance,                                      must resume routine monitoring. For
                                       collect at least one sample among the                         although monitoring requirements may                              systems with annual or less frequent
                                       total number of samples required for the                      not be reduced.
                                                                                                                                                                       reduced monitoring, systems may
                                       combined distribution system and will                            i. Reduced monitoring. Systems can
                                                                                                     qualify for reduced monitoring, as                                remain on reduced monitoring as long
                                       base compliance on samples collected
                                       within its distribution system. The                           specified in Table IV.G–3, if the LRAA                            as each TTHM sample is ≤0.060 mg/L
                                       consecutive system is responsible for                         at each location is ≤0.040 mg/L for                               and each HAA5 sample is ≤0.045 mg/L.
                                       ensuring that required monitoring is                          TTHM and ≤0.030 mg/L for HAA5 based                               If the annual (or less frequent) sample
                                       completed and the system is in                                on at least one year of monitoring at                             at any location exceeds either 0.060 mg/
                                       compliance. It also must document its                         routine compliance monitoring                                     L for TTHM or 0.045 mg/L for HAA5,
                                       monitoring strategy as part of its subpart                    locations. Systems may remain on                                  or if the source water annual average
                                       V monitoring plan.                                            reduced monitoring as long as the                                 TOC level, before any treatment,
                                          Consecutive systems not already                            TTHM LRAA is ≤0.040 mg/L and the                                  exceeds 4.0 mg/L at any treatment plant
                                       conducting disinfectant residual                              HAA5 LRAA is ≤0.030 mg/L at each                                  treating surface water or ground water
                                       monitoring under the Stage 1 DBPR                             monitoring location for systems with                              under the direct influence of surface
                                       must comply with the monitoring                               quarterly reduced monitoring. If the                              water, the system must resume routine
                                       requirements and MRDLs for chlorine                           LRAA at any location exceeds either                               monitoring.

                                                                                         TABLE IV.G–3.—REDUCED MONITORING FREQUENCY
                                                                Population size cat-              Monitoring fre-
                                        Source water type                                                                                   Distribution system monitoring location per monitoring period
                                                                      egory                         quency 1
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                                       Subpart H:
                                                                <500 ......................       ...........................     Monitoring may not be reduced.

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                                       428               Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                                                              TABLE IV.G–3.—REDUCED MONITORING FREQUENCY—Continued
                                                                Population size cat-             Monitoring fre-
                                        Source water type                                                                              Distribution system monitoring location per monitoring period
                                                                      egory                        quency 1

                                                                500–3,300 .............       per year .................     1 TTHM and 1 HAA5 sample: one at the location and during the quarter with
                                                                                                                               the highest TTHM single measurement, one at the location and during the
                                                                                                                               quarter with the highest HAA5 single measurement; 1 dual sample set per
                                                                                                                               year if the highest TTHM and HAA5 measurements occurred at the same
                                                                                                                               location and quarter.
                                                                3,301–9,999 ..........        per year .................     2 dual sample sets: one at the location and during the quarter with the highest
                                                                                                                               TTHM single measurement, one at the location and during the quarter with
                                                                                                                               the highest HAA5 single measurement.
                                                                10,000–49,999 ......          per quarter ............       2 dual sample sets at the locations with the highest TTHM and highest HAA5
                                                                50,000–249,999 ....           per quarter ............       4 dual sample sets—at the locations with the two highest TTHM and two high-
                                                                                                                               est HAA5 LRAAs.
                                                                250,000–999,999 ..            per quarter ............       6 dual sample sets—at the locations with the three highest TTHM and three
                                                                                                                               highest HAA5 LRAAs
                                                                1,000,000–                    per quarter ............       8 dual sample sets—at the locations with the four highest TTHM and four
                                                                  4,999,999.                                                   highest HAA5 LRAAs.
                                                                ≥5,000,000 ............       per quarter ............       10 dual sample sets—at the locations with the five highest TTHM and five
                                                                                                                               highest HAA5 LRAAs.
                                       Ground Water:
                                                                <500 ......................   every third year .....         1 TTHM and 1 HAA5 sample: one at the location and during the quarter with
                                                                                                                               the highest TTHM single measurement, one at the location and during the
                                                                                                                               quarter with the highest HAA5 single measurement; 1 dual sample set per
                                                                                                                               year if the highest TTHM and HAA5 measurements occurred at the same
                                                                                                                               location and quarter.
                                                                500–9,999 .............       per year .................     1 TTHM and 1 HAA5 sample: one at the location and during the quarter with
                                                                                                                               the highest TTHM single measurement, one at the location and during the
                                                                                                                               quarter with the highest HAA5 single measurement; 1 dual sample set per
                                                                                                                               year if the highest TTHM and HAA5 measurements occurred at the same
                                                                                                                               location and quarter.
                                                                10,000–99,999 ......          per year .................     2 dual sample sets: one at the location and during the quarter with the highest
                                                                                                                               TTHM single measurement, one at the location and during the quarter with
                                                                                                                               the highest HAA5 single measurement.
                                                                100,000–499,999 ..            per quarter ............       2 dual sample sets; at the locations with the highest TTHM and highest HAA5
                                                                ≥500,000 ...............      per quarter ............       4 dual sample sets at the locations with the two highest TTHM and two high-
                                                                                                                               est HAA5 LRAAs.
                                          1 Systems   on quarterly monitoring must take dual sample sets every 90 days.

                                          ii. Compliance determination. A PWS                       the wholesale system fails to monitor,                      the impacts of using the population-
                                       is in compliance when the annual                             the consecutive system is in violation                      based approach.
                                       sample or LRAA of quarterly samples is                       because it has the legal responsibility                        The plant-based approach was
                                       less than or equal to the MCLs. If an                        for monitoring under State/EPA                              adopted from the 1979 TTHM rule and
                                       annual sample exceeds the MCL, the                           regulations.                                                the Stage 1 DBPR and was derived from
                                       system must conduct increased                                  • If a wholesale system has a                             the generally valid assumption that, as
                                       (quarterly) monitoring but is not                            violation and provides that water to a                      systems increase in size, they tend to
                                       immediately in violation of the MCL.                         consecutive system, the wholesale                           have more plants and increased
                                       The system is out of compliance if the                       system is in violation. Whether the                         complexity. During the development of
                                       LRAA of the quarterly samples for the                        consecutive system is in violation will                     the Stage 2 proposal, EPA identified a
                                       past four quarters exceeds the MCL.                          depend on the situation. The                                number of issues associated with the
                                          Monitoring and MCL violations are                         consecutive system will also be in                          use of the plant-based monitoring
                                       assigned to the PWS where the violation                      violation unless it conducted                               approach. These included: (1) Plant-
                                       occurred. Several examples are as                            monitoring that showed that the                             based monitoring is not as effective as
                                       follows:                                                     violation was not present in the                            population-based monitoring in
                                          • If monitoring results in a                              consecutive system.                                         targeting locations with the highest risk;
                                       consecutive system indicate an MCL                                                                                       (2) a plant-based approach can result in
                                       violation, the consecutive system is in                      2. Background and Analysis                                  disproportionate monitoring
                                       violation because it has the legal                             EPA proposed the plant-based                              requirements for systems serving the
                                       responsibility for complying with the                        approach for all systems that produce                       same number of people (due to widely
                                       MCL under State/EPA regulations. The                         some or all of their finished water and                     varying numbers of plants per system);
                                       consecutive system may set up a                              the population-based monitoring                             (3) it cannot be adequately applied to
                                       contract with its wholesale system that                      approach for systems purchasing all of                      plants or consecutive system entry
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                                       details water quality delivery                               their finished water year-round. As part                    points that are operated seasonally or
                                       specifications.                                              of the proposal, EPA presented a                            intermittently if an LRAA is used for
                                          • If a consecutive system has hired its                   monitoring cost analysis for applying                       compliance due to complex
                                       wholesale system under contract to                           this approach to all systems in the                         implementation and a need for repeated
                                       monitor in the consecutive system and                        Economic Analysis to better understand                      transactions between the State and

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                                       system to determine whether and how                                                 Compared to the 1995 CWSS, the 2000                          (serving fewer than 10,000 people) and
                                       compliance monitoring requirements                                                  CWSS contained questions more                                the ranges have been modified to be
                                       may need to be changed; (4) State                                                   relevant for determining the number of                       consistent with those for other existing
                                       determinations of monitoring                                                        plants in each system. Based on 2000                         rules (such as the Lead and Copper
                                       requirements for consecutive systems                                                CWSS data, EPA has modified the                              Rule). This change will reduce
                                       would be complicated, especially in                                                 number of monitoring sites per system                        implementation transactional costs. For
                                       large combined distribution systems                                                 for several categories (particularly for                     medium and large subpart H systems
                                       with many connections between                                                       the larger subpart H systems) to align                       (serving at least 10,000 people), EPA has
                                       systems; and (5) systems with multiple                                              the median population-based                                  gone from seven categories in the
                                       disinfecting wells would have to                                                    monitoring requirements with the                             proposal to five categories in final rule.
                                       conduct evaluation of common aquifers                                               median monitoring requirements under                         The population groups are sized so that
                                       in order to avoid taking unnecessary                                                plant-based monitoring, as was                               the ratio of maximum population to
                                       samples for compliance (if they did not                                             proposed.                                                    minimum population for each of the
                                       conduct such evaluations under Stage                                                   EPA also believes that more samples                       categories is consistent. EPA believes
                                       1). EPA requested comment on two                                                    are necessary to characterize larger                         that this will allow most systems to
                                       approaches to address these issues: (1)                                             systems (as defined by population) than                      remain in one population size category
                                       keep the plant-based monitoring                                                     for smaller systems. This progressive                        and maintain the same monitoring
                                       approach and add new provisions to                                                  approach is included in Table IV.G–4.                        requirements within a reasonable range
                                       address specific concerns; and (2) base                                             As system size increases, the number of                      of population variation over time. In
                                       monitoring requirements on source                                                   samples increases to better reflect the                      addition, it assures that systems within
                                       water type and population served, in                                                hydraulic complexity of these systems.                       a size category will not have disparate
                                       lieu of plant-based monitoring.                                                     While the national monitoring burden                         monitoring burdens as could occur if
                                                                                                                           under the population-based approach is                       there were too few categories. Overall,
                                          The final rule’s requirements of                                                 slightly less than under a plant-based
                                       population-based monitoring for all                                                                                                              EPA believes that the population-based
                                                                                                                           approach, some larger systems with few                       monitoring approach allows systems to
                                       systems are based on improved public                                                plants relative to system population will
                                       health protection, flexibility, and                                                                                                              have more flexibility to designate their
                                                                                                                           take more samples per system than they
                                       simplified implementation. For                                                                                                                   monitoring sites within the distribution
                                                                                                                           had under plant-based monitoring.
                                       determining monitoring requirements,                                                                                                             system to better target high DBP levels
                                                                                                                           However, EPA believes that many of
                                       EPA’s objective was to maintain                                                                                                                  and is more equitable.
                                                                                                                           these large systems with few plants have
                                       monitoring loads consistent with Stage                                              traditionally been undermonitored (as                           To derive the number of monitoring
                                       1 and similar to monitoring loads                                                   noted in the proposal). Systems with                         sites for IDSE standard monitoring, EPA
                                       proposed for Stage 2 under a plant-                                                 more plants will see a reduction in                          doubled the number of routine
                                       based approach, using a population-                                                 monitoring (e.g., small ground water                         compliance monitoring sites per system
                                       based approach to facilitate                                                        systems with multiple wells).                                for each size category. This is consistent
                                       implementation, better target high DBP                                                 While population-based monitoring                         with the advice and recommendations
                                       levels, and protect human health. This                                              requirements for ground water systems                        of the M-DBP Advisory Committee for
                                       leads to a more cost-effective                                                      in today’s rule remain the same as those                     the IDSE. EPA has developed the Initial
                                       characterization of where high levels                                               in the proposed rule, the final rule                         Distribution System Evaluation
                                       occur. For the proposed rule, EPA used                                              consolidates ten population categories                       Guidance Manual for the Final Stage 2
                                       1995 CWSS data to derive the number                                                 for subpart H systems into eight                             Disinfectants and Disinfection
                                       of plants per system for calculating the                                            categories for ease of implementation.                       Byproducts Rule (USEPA 2006) to assist
                                       number of proposed monitoring sites                                                 As indicated in Table IV.G–4, EPA has                        systems in choosing IDSE monitoring
                                       per system. During the comment period,                                              gone from four to three population size                      locations, including criteria for selecting
                                       2000 CWSS data became available.                                                    categories for smaller subpart H systems                     monitoring.
                                                                  MONITORING WITH PLANT-BASED AND POPULATION-BASED APPROACHES
                                                                                                                                                      Plant-based      Number of plants per sys-    Calculated number of sites
                                                                                                                                                       approach*         tem (Based on 2000         per system for plant-based   Number of
                                                                                                                   Ratio of             Number of                           CWSS data)                       approach            monitoring
                                                                                                                  maximum                sampling                                                                                 sites per
                                                           Population category                                    population            periods per                                                 Based on       Based on      system for
                                                                                                                 to minimum                           # Sites per
                                                                                                                                           year                                                     median #        mean #       pop-based
                                                                                                                  population                             plant          Median         Mean         plants per     plants per    approach
                                                                                                                                                                                                     system         system

                                                                                                                                            A              B               C             D            E=B*C         F=B*D            G

                                       <500 ..................................................................   ....................             1            **1               1           1.21              1           1.2           **1
                                       500–3,300 .........................................................                      6.6               4            **1               1           1.22              1           1.2           **1
                                       3,301–9,999 ......................................................                          3              4              2               1           1.56              2           3.1             2
                                       10,000–49,999 ..................................................                            5              4              4               1           1.37              4           5.5             4
                                       50,000–249,999 ................................................                             5              4              4               1           1.83              4           7.3             8
                                       250,000–<1 million ............................................                             4              4              4               2           2.53              8          10.1            12
                                       1 million–<5 million ...........................................                            5              4              4               4           3.62             16          14.5            16
                                       ≥5 million ...........................................................    ....................             4              4               4           4.33             16          17.3            20
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                                         * As in the proposal.
                                         ** System is required to take individual TTHM and HAA5 samples at the locations with the highest TTHM and HAA5 concentrations, respectively, if highest TTHM
                                       and HAA5 concentrations do not occur at the same location.

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                                         Note: To determine the number of routine compliance monitoring sites per population category, EPA took these steps: (1) Maintaining about the same sampling
                                       loads in the nation as required under the plant-based approach, but basing on population rather than number of plants to better target high DBP levels in distribution
                                       systems and facilitate implementation; (2) The number of monitoring sites per plant under the plant-based approach (Column B) were multiplied by the number of
                                       plants per system (Columns C and D) to calculate the number of monitoring sites per system under the plant-based approach (Columns E and F in terms of median
                                       and mean, respectively); and (3) The number of monitoring sites per system under the population-based approach were derived with adjustments to keep categories
                                       consistent and to maintain an even incremental trend as the population size category increases (Column G).

                                       3. Summary of Major Comments                            for complicated distribution system                     eases the complexity by specifying
                                          EPA received significant support for                 relationships, such as where                            minimum system-level requirements;
                                       applying the population-based approach                  neighboring systems buy from and sell                   simplicity is essential for meeting the
                                       to all systems. EPA also received                       to each other regularly throughout the                  implementation schedule in today’s
                                       comments concerning the specific                        year. In this case, water may pass                      rule. If monitoring requirements were
                                       requirements in a population-based                      through multiple consecutive systems                    determined by the combined
                                       approach.                                               before it reaches a user. Another                       distribution system population, many
                                          Excessive Sampling Requirements.                     example would be a large group of                       implementation problems would occur.
                                       Several commenters believed that the                    interconnected systems that have a                      Some of these problems would have the
                                       proposed sampling requirements were                     complicated combined distribution                       potential to impact public health
                                       excessive (especially in the larger                     system. This approach also allows the                   protection. For example, States or
                                       population categories for subpart H                     combined distribution system to                         primacy agencies would have to decide
                                       systems) and that some individual                       concentrate IDSE and Stage 2                            how to allocate IDSE distribution
                                       systems would be required to sample                     monitoring sites in the system with the                 system samples (where and how much
                                       more under the population-based                         highest known DBP concentrations,                       to monitor in individual PWSs) in a
                                       approach than the plant-based                           while assigning fewer sample sites to                   complicated combined distribution
                                       approach. EPA recognizes that a small                   systems with low DBP concentrations.                    system with many systems, multiple
                                       fraction of systems in some categories                     Population Size Categories. Some                     sources, multiple treatment plants, and
                                       will have to take more samples under                    commenters recommended fewer                            varying water demand and with limited
                                       the population-based approach than the                  population categories for subpart H                     understanding of DBP levels throughout
                                       plant-based approach because their                      systems (those using surface water or                   the combined distribution system. This
                                       number of plants is substantially less                  ground water under the direct influence                 would have to happen shortly after rule
                                       than the national median or mean.                       of surface water as a source) than                      promulgation in order to meet the
                                       However, the number of samples                          proposed while others recommended                       schedule. For example, some
                                       required under the Stage 1 DBPR for                     more. Today’s rule has fewer categories                 consecutive systems buy water
                                       these systems may not have been                         than proposed. However, EPA believes                    seasonally (in times of high water
                                       sufficient to determine the                             that further reduction of the number of                 demand) or buy from more than one
                                       concentrations of DBPs throughout the                   population size categories will not                     wholesale system (with the volume
                                       distribution system of these systems. On                reflect the fact that the number of plants              purchased based on many factors). The
                                       the other hand, systems with many                       and complexity of distribution systems                  State or primacy agency would find it
                                       plants may have taken excessive                         (and DBP exposure) tend to increase as                  difficult to properly assign a limited
                                       samples under the Stage 1 DBPR that                     the population served increases. As a                   number of IDSE monitoring locations
                                       were not necessary to appropriately                     result, the population served by a large                (especially since there are States where
                                       determine DBP levels throughout the                     system in one particular category would                 many consecutive systems have no DBP
                                       distribution system. Consequently, the                  receive much less protection from the                   data) to adequately reflect DBP levels in
                                       total number of samples taken                           DBP risks than a smaller system in the                  such a system, as well as throughout the
                                       nationally will be comparable to the                    same size category. On the other hand,                  combined distribution system.
                                       Stage 1 DBPR, but will better target DBP                too many categories with smaller                           EPA believes that assigning
                                       risks in individual distribution systems.               population ranges would result in                       compliance monitoring requirements
                                          Consecutive systems. Some                            frequent category and requirement shifts                appropriately throughout the combined
                                       commenters noted that a consecutive                     as population fluctuates. Much greater                  distribution system requires a case-by-
                                       system may need to take more samples                    implementation effort would be needed                   case determination based on factors
                                       than its associated wholesale system.                   for those systems without much benefit                  such as amount and percentage of
                                       Under today’s rule, all systems,                        in DBP exposure knowledge.                              finished water provided; whether
                                       including consecutive systems, must                        Population Definition. Some                          finished water is provided seasonally,
                                       monitor based on retail population                      commenters supported use of the                         intermittently, or full-time; and
                                       served. Thus, large consecutive systems                 population of a combined distribution                   improved DBP occurrence information.
                                       will take more samples than a smaller                   system (i.e., the wholesale and                         Since the IDSE will provide improved
                                       wholesale system. The population-based                  consecutive systems should be                           DBP occurrence information throughout
                                       monitoring approach will allow the                      considered a single system for                          the combined distribution system,
                                       samples to better represent the DBP                     monitoring purposes) while others                       States may consider modifications to
                                       concentrations consumed by the                          preferred use of the retail population for              Stage 2 compliance monitoring
                                       population associated with the sampling                 each individual system (i.e., wholesale                 requirements for consecutive systems on
                                       locations and to understand the DBP                     systems and consecutive systems are                     a case-by-case basis as allowed by
                                       concentrations reaching consumers.                      considered separately). Today’s final                   § 141.29 or under the special primacy
                                       There is also a provision that allows                   rule uses the retail population for each                condition at § 142.16(m)(3) by taking all
                                       States to specify alternative monitoring                individual system. EPA chose this                       these factors into consideration. In
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                                       requirements for a consecutive system                   approach for today’s rule because of the                making these case-by-case
                                       in a combined distribution system (40                   complexity involved in making                           determinations, the State will be able to
                                       CFR 142.16(m)(3)). This special primacy                 implementation decisions for                            use its system-specific knowledge, along
                                       condition allows the State to establish                 consecutive systems. Using the retail                   with the IDSE results, to develop an
                                       monitoring requirements that account                    population to determine requirements                    appropriate monitoring plan for each

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                            431

                                       system within the combined                              1. Today’s Rule                                        operational evaluation does not extend
                                       distribution system.                                       Today’s rule defines the Stage 2 DBP                the schedule (90 days after notification
                                          Changes to monitoring plans.                         operational evaluation levels that                     of the analytical result) for submitting
                                       Commenters requested more specific                      require systems to conduct operational                 the operational evaluation report.
                                       language regarding how IDSE and Stage                   evaluations. The Stage 2 DBP                           2. Background and Analysis
                                       2 monitoring plans should be updated                    operational evaluation levels are
                                       as a result of treatment or population                                                                            The Stage 2 DBPR proposal outlined
                                                                                               identified using the system’s Stage 2                  three components of the requirements
                                       changes in the distribution system.                     DBPR compliance monitoring results.
                                       Changes to IDSE plans should not be                                                                            for significant excursions (definition,
                                                                                               The operational evaluation levels for                  system evaluation and excursion
                                       necessary since the State or primacy                    each monitoring location are
                                       agency will have reviewed those plans                                                                          report). In response to public comments,
                                                                                               determined by the sum of the two                       the term ‘‘significant excursion’’ has
                                       shortly before the system must conduct                  previous quarters’ TTHM results plus
                                       the IDSE and the reviewed plan should                                                                          been replaced by the term ‘‘operational
                                                                                               twice the current quarter’s TTHM result,               evaluation level’’ in today’s rule. The
                                       identify such issues. EPA provided a                    at that location, divided by 4 to
                                       process in the Stage 2 DBPR proposal                                                                           evaluation and report components
                                                                                               determine an average and the sum of the                remain the same as those outlined in the
                                       for updating monitoring plans for                       two previous quarters’ HAA5 results
                                       systems that have significant changes to                                                                       proposed rule for significant excursions.
                                                                                               plus twice the current quarter’s HAA5                  However, the scope of the evaluation
                                       treatment or in the distribution system                 result, at that location, divided by 4 to
                                       after they complete their IDSE. This                                                                           and report components of the
                                                                                               determine an average. If the average                   operational evaluation has also been
                                       process remains in today’s rule, with an                TTHM exceeds 0.080 mg/L at any
                                       added requirement that systems must                                                                            modified from the proposed significant
                                                                                               monitoring location or the average                     excursion evaluation components based
                                       consult with the State or primacy                       HAA5 exceeds 0.060 mg/L at any                         on public comments.
                                       agency to determine whether the                         monitoring location, the system must                      In the Stage 2 DBPR proposal, States
                                       changes are necessary and appropriate                   conduct an operational evaluation and                  were to define criteria to identify
                                       prior to implementing changes to their                  submit a written report of the                         significant excursions rather than using
                                       Stage 2 monitoring plan.                                operational evaluation to the State.                   criteria defined by EPA. Concurrent
                                          In addition, the State or primacy                       Operational evaluation levels                       with the Stage 2 DBPR proposal, EPA
                                       agency may require a system to revise                   (calculated at each monitoring location)               issued draft guidance (USEPA 2003e)
                                       its IDSE plan, IDSE report, or Stage 2                     IF (Q1 + Q2 + 2Q3)/4> MCL, then the                 for systems and States that described
                                       monitoring plan at any time. This                       system must conduct an operational                     how to determine whether a significant
                                       change was made so that systems could                   evaluation                                             excursion has occurred, using several
                                       receive system-specific guidance from                   where:                                                 different options. The rule proposal
                                       the State or primacy agency on the                                                                             specifically requested public comment
                                       appropriate revisions to the Stage 2                       Q3 = current quarter measurement
                                                                                                  Q2 = previoius quarter measurement                  on the definition of a significant
                                       monitoring plan. Regulatory language                                                                           excursion, whether it should be defined
                                       regarding changes that might occur is                      Q1 = quarter before previous quarter
                                                                                                    measurement                                       by the State or nationally, and the scope
                                       not appropriate because any                                                                                    of the evaluation.
                                       modifications would be system-specific                    MCL = Stage 2 MCL for TTHM (0.080                       After reviewing comments on the
                                       and a national requirement is not                       mg/l) or Stage 2 MCL for HAA5 (0.060                   Stage 2 DBPR proposal, EPA determined
                                       capable of addressing these system-                     mg/L)                                                  that DBP levels initiating an operational
                                       specific issues.                                          The operational evaluation includes                  evaluation should be defined in the
                                                                                               an examination of system treatment and                 regulation to ensure national
                                       H. Operational Evaluation
                                                                                               distribution operational practices,                    consistency. Systems were concerned
                                       Requirements Initiated by TTHM and
                                                                                               including changes in sources or source                 with the evaluation requirements being
                                       HAA5 Levels
                                                                                               water quality, storage tank operations,                initiated based on criteria that might not
                                          A system that is in full compliance                  and excess storage capacity, that may                  be consistent nationally. Also, many
                                       with the Stage 2 DBPR LRAA MCL may                      contribute to high TTHM and HAA5                       States believed the requirement for
                                       still have individual DBP measurements                  formation. Systems must also identify                  States to define criteria to initiate an
                                       that exceed the Stage 2 DBPR MCLs,                      what steps could be considered to                      evaluation would be difficult for States
                                       since compliance is based on individual                 minimize future operational evaluation                 to implement.
                                       DBP measurements at a location                          level exceedences. In cases where the                     Under today’s rule, EPA is defining
                                       averaged over a four-quarter period.                    system can identify the cause of DBP                   operational evaluation levels with an
                                       EPA and the Advisory Committee were                     levels that resulted in the operational                algorithm based on Stage 2 DBPR
                                       concerned about these higher levels of                  evaluation, based on factors such as                   compliance monitoring results. These
                                       DBPs. This concern was clearly                          water quality data, plant performance                  operational evaluation levels will act as
                                       reflected in the Agreement in Principle,                data, and distribution system                          an early warning for a possible MCL
                                       which states, ‘‘. . . significant                       configuration the system may request                   violation in the following quarter. This
                                       excursions of DBP levels will sometimes                 and the State may allow limiting the                   early warning is accomplished because
                                       occur, even when systems are in full                    evaluation to the identified cause. The                the operational evaluation requirement
                                       compliance with the enforceable                         State must issue a written determination               is initiated when the system assumes
                                       MCL. . .’’.                                             approving limiting the scope of the                    that the current quarter’s result is
                                          Today’s final rule addresses this                    operational evaluation. The system must                repeated and this will result in an MCL
                                       concern by requiring systems to conduct                 submit their operational evaluation                    violation. This early identification
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                                       operational evaluations that are initiated              report to the State for review within 90               allows the system to act to prevent the
                                       by operational evaluation levels                        days after being notified of the                       violation.
                                       identified in Stage 2 DBPR compliance                   analytical result that initiates the                      Today’s rule also modifies the scope
                                       monitoring and to submit an operational                 operational evaluation. Requesting                     of an operational evaluation. EPA has
                                       evaluation report to the State.                         approval to limit the scope of the                     concluded that the source of DBP levels

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                                       432               Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                       that would initiate an operational                      DBP levels that might not be warranted                 distribution systems, as in the proposal.
                                       evaluation can potentially be linked to                 rather than on system operational issues               Others felt that the treatment processes
                                       a number of factors that extend beyond                  and compliance with Stage 2 DBPR                       should be included in the evaluation,
                                       distribution system operations.                         MCLs.                                                  noting that these can be significant in
                                       Therefore, EPA believes that evaluations                   Basis. The proposed requirements for                the formation of DBPs.
                                       must include a consideration of                         significant excursion evaluations were                    The Agency agrees with commenters
                                       treatment plant and other system                        not based upon health effects, but rather              that treatment processes can be a
                                       operations rather than limiting the                     were intended to be an indicator of                    significant factor in DBP levels initiating
                                       operational evaluation to only the                      operational performance. To address                    an operational evaluation and that a
                                       distribution system, as proposed.                       commenter’s concerns and to emphasize                  comprehensive operational evaluation
                                       Because the source of the problem could                 what EPA believes should initiate a                    should address treatment processes. In
                                       be associated with operations in any of                 comprehensive evaluation of system                     cases where the system can clearly
                                       these system components (or more than                   operations that may result in elevated                 identify the cause of the DBP levels
                                       one), an evaluation that provides                       DBP levels and provide a proactive                     initiating an operational evaluation
                                       systems with valuable information to                    procedure to address compliance with                   (based on factors such as water quality
                                       evaluate possible modifications to                      Stage 2 DBP LRAA MCLs , EPA has                        data, plant performance data,
                                       current operational practices (e.g. water               replaced the term ‘‘significant                        distribution system configuration, and
                                       age management, source blending) or in                  excursion’’ used in the Stage 2 DBPR                   previous evaluations) the State may
                                       planning system modifications or                        proposal with the term ‘‘operational                   allow the system to limit the scope of
                                       improvements (e.g. disinfection                         evaluation level’’ in today’s rule.                    the evaluation to the identified cause. In
                                       practices, tank modifications,                             Definition of the operational                       other cases, it is appropriate to evaluate
                                       distribution looping) will reduce DBP                   evaluation levels. The majority of                     the entire system, from source through
                                       levels initiating an operational                        commenters stated that EPA should                      treatment to distribution system
                                       evaluation. EPA also believes that State                define the DBP levels initiating an                    configuration and operational practices.
                                       review of operational evaluation reports                operational evaluation (‘‘significant                     Timing for completion and review of
                                       is valuable for both States and systems                 excursion’’ in the proposal) in the                    the evaluation report. While some
                                       in their interactions, particularly when                regulation to ensure national                          commenters agreed that the evaluation
                                       systems may be in discussions with or                   consistency rather than requiring States               report should be reviewed as part of the
                                       requesting approvals from the State for                 to develop their own criteria (as was                  sanitary survey process (as proposed),
                                       system improvements. Timely reviews                     proposed). Commenters suggested                        many commenters felt that the time
                                       of operational evaluation reports will be               several definitions, including a single                between sanitary surveys (up to five
                                       valuable for States in reviewing other                  numerical limit and calculations                       years) minimized the value of the
                                       compliance submittals and will be                       comparing previous quarterly DBP                       evaluation report in identifying both the
                                       particularly valuable in reviewing and                  results to the current quarter’s result.               causes of DBP levels initiating an
                                       approving any proposed source,                          Commenters that recommended a single                   operational evaluation and in possible
                                       treatment or distribution system                        numerical limit felt that such an                      changes to prevent recurrence.
                                       modifications for a water system. Under                 approach was justified by the available                Moreover, a number of commenters felt
                                       today’s rule, systems must submit a                     health effects information, while other                that the evaluation report was important
                                       written report of the operational                       commenters felt available heath effects                enough to warrant a separate submittal
                                       evaluation to the State no later than 90                information did not support a single                   and State review rather than have the
                                       days after being notified of the DBP                    numerical limit. Commenters                            evaluation report compete with other
                                       analytical result initiating an                         recommended that any definition be                     priorities during a sanitary survey.
                                       operational evaluation. The written                     easy to understand and implement.                         The Agency agrees that completion
                                       operational evaluation report must also                    EPA agrees with commenter                           and State review of evaluation reports
                                       be made available to the public upon                    preference for national criteria to                    on a three or five year sanitary survey
                                       request.                                                initiate an operational evaluation. The                cycle, when the focus of the evaluation
                                                                                               DBP levels initiating an operational                   is on what may happen in the next
                                       3. Summary of Major Comments                            evaluation in today’s rule consider                    quarter, would allow for an
                                          EPA received comments both in favor                  routine operational variations in                      unreasonable period of time to pass
                                       of and opposed to the proposed                          distribution systems, are simple for                   between the event initiating the
                                       evaluation requirements. While some                     water systems to calculate, and                        operational evaluation and completion
                                       commenters felt that the evaluation                     minimize the implementation burden                     and State review of the report. This
                                       requirements should not be a part of the                on States. They also provide an early                  would diminish the value of the
                                       Stage 2 DBPR until there was more                       warning to help identify possible future               evaluation report for both systems and
                                       information regarding potential health                  MCL violations and allow the system to                 States, particularly when systems may
                                       effects correlated to specific DBP levels,              take proactive steps to remain in                      be in discussions with or requesting
                                       other commenters felt that the existing                 compliance. EPA emphasizes, as it did                  approval for treatment changes from
                                       health effects data were sufficient to                  in the proposal and elsewhere in this                  States, and as noted above, the focus of
                                       warrant strengthening the proposed                      notice, that health effects research is                the report is on what may occur in the
                                       requirements for an evaluation. Today’s                 insufficient to identify a level at which              next quarter. EPA believes that timely
                                       final rule requirements are consistent                  health effects occur, and thus today’s                 reviews of evaluation reports by States
                                       with the Agreement in Principle                         methodology for initiating operational                 is important, would be essential for
                                       recommendations.                                        evaluation is not based upon health                    States in understanding system
                                          Some commenters noted that health                    effects, but rather is intended as an                  operations and reviewing other
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                                       effects research on DBPs is insufficient                indicator of operational performance.                  compliance submittals, and would be
                                       to identify a level at which health                        Scope of an evaluation. Some                        extremely valuable in reviewing and
                                       effects occur and were concerned that                   commenters felt that the scope of an                   approving any proposed source,
                                       the proposed significant excursion                      evaluation initiated by locational DBP                 treatment or distribution system
                                       requirements placed an emphasis on                      levels should be limited to the                        modifications for a water system.

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                             433

                                       Having the evaluation information on an                 utilization of alternative technologies,               2. Background and Analysis
                                       ongoing basis rather than a delayed                     such as UV, and whether the risk/risk                     EPA requested comment on including
                                       basis would also allow States to                        concerns reflected in today’s rule, as                 language in the proposed rule
                                       prioritize their resources in scheduling                well as in the LT2ESWTR, remain valid.                 concerning potential reproductive and
                                       and reviewing particular water system                      b. Criterion for reduced bromate                    developmental health effects. EPA
                                       operations and conditions as part of any                monitoring. Because more sensitive                     believes this is an important issue
                                       on-site system review or oversight.                     bromate methods are now available,                     because of the large population exposed
                                       Therefore, today’s rule requires that                   EPA is requiring a new criterion for                   (58 million women of child-bearing age;
                                       systems complete the operational                        reduced bromate monitoring. In the                     USEPA 2005a) and the number of
                                       evaluation and submit the evaluation                    Stage 1 DBPR, EPA required ozone                       studies that, while not conclusive, point
                                       report to the State within 90 days of the               systems to demonstrate that source                     towards a potential risk concern. While
                                       occurrence.                                             water bromide levels, as a running                     EPA is not including information about
                                                                                               annual average, did not exceed 0.05 mg/                reproductive and developmental health
                                       I. MCL, BAT, and Monitoring for
                                                                                               L. EPA elected to use bromide as a                     effects in public notices at this time, the
                                                                                               surrogate for bromate in determining                   Agency plans to reconsider whether to
                                       1. Today’s Rule                                         eligibility for reduced monitoring                     include this information in the future.
                                          Today EPA is confirming that the                     because the available analytical method                As part of this effort, EPA intends to
                                       MCL for bromate for systems using                       for bromate was not sensitive enough to                support research to assess
                                       ozone remains at 0.010 mg/L as an RAA                   quantify levels well below the bromate                 communication strategies on how to
                                       for samples taken at the entrance to the                MCL of 0.010 mg/L.                                     best provide this information.
                                       distribution system as established by the                  EPA approved several new analytical                    The responsibilities for public
                                       Stage 1 DBPR. Because the MCL remains                   methods for bromate that are far more                  notification and consumer confidence
                                       the same, EPA is not modifying the                      sensitive than the existing method as                  reports rest with the individual system.
                                       existing bromate BAT. EPA is changing                   part of today’s rule. Since these methods              Under the Public Notice Rule (Part 141
                                       the criterion for a system using ozone to               can measure bromate to levels of 0.001                 subpart Q) and Consumer Confidence
                                       qualify for reduced bromate monitoring                  mg/L or lower, EPA is replacing the                    Report Rule (Part 141 subpart O), the
                                       from demonstrating low levels of                        criterion for reduced bromate                          wholesale system is responsible for
                                       bromide to demonstrating low levels of                  monitoring (source water bromide                       notifying the consecutive system of
                                       bromate.                                                running annual average not to exceed                   analytical results and violations related
                                                                                               0.05 mg/L) with a bromate running                      to monitoring conducted by the
                                       2. Background and Analysis                              annual average not to exceed 0.0025 mg/                wholesale system. Consecutive systems
                                          a. Bromate MCL. Bromate is a                         L.                                                     are required to conduct appropriate
                                       principal byproduct from ozonation of                      In the past, EPA has often set the                  public notification after a violation
                                       bromide-containing source waters. As                    criterion for reduced monitoring                       (whether in the wholesale system or the
                                       described in more detail in the Stage 2                 eligibility at 50% of the MCL, which                   consecutive system). In their consumer
                                       DBPR proposal (USEPA 2003a), more                       would be 0.005 mg/L. However, the                      confidence report, consecutive systems
                                       stringent bromate MCL has the potential                 MCL for bromate will remain at 0.010                   must include results of the testing
                                       to decrease current levels of microbial                 mg/L, representing a risk level of 2×10/               conducted by the wholesale system
                                       protection, impair the ability of systems               b 2×10¥4, 10¥4 and 10¥6 (higher than                   unless the consecutive system
                                       to control resistant pathogens like                     EPA’s usual excess cancer risk range of                conducted equivalent testing (as
                                       Cryptosporidium, and increase levels of                 10¥4 to 10¥6) because of risk tradeoff                 required in today’s rule) that indicated
                                       DBPs from other disinfectants that may                  considerations) (USEPA 2003a).                         the consecutive system was in
                                       be used instead of ozone. EPA                              EPA believes that the decision for                  compliance, in which case the
                                       considered reducing the bromate MCL                     reduced monitoring is separate from                    consecutive system reports its own
                                       from 0.010 mg/L to 0.005 mg/L as an                     these risk tradeoff considerations. Risk               compliance monitoring results.
                                       annual average but concluded that many                  tradeoff considerations influence the
                                       systems using ozone to inactivate                       selection of the MCL, while reduced                    3. Summary of Major Comments
                                       microbial pathogens would have                          monitoring requirements are designed to                   EPA requested and received many
                                       significant difficulty maintaining                      ensure that the MCL, once established,                 comments on the topic of including
                                       bromate levels at or below 0.005 mg/L.                  is reliably and consistently achieved.                 public notification language regarding
                                       In addition, because of the high doses                  Requiring a running annual average of                  potential reproductive and
                                       required, the ability of systems to use                 0.0025 mg/L for the reduced monitoring                 developmental effects. A number of
                                       ozone to meet Cryptosporidium                           criterion allows greater confidence that               comments called for including
                                       treatment requirements under the                        the system is achieving the MCL and                    reproductive and developmental health
                                       LT2ESWTR would be diminished if the                     thus ensuring public health protection.                effects language to address the potential
                                       bromate MCL was decreased from 0.010                    3. Summary of Major Comments                           health concerns that research has
                                       to 0.005 mg/L; higher doses will                                                                               shown. Numerous comments also
                                       generally lead to greater bromate                         Commenters supported both the                        opposed such language due to
                                       formation. After evaluation under the                   retention of the existing bromate MCL                  uncertainties in the underlying science
                                       risk-balancing provisions of section                    and the modified reduced monitoring                    and the implications such language
                                       1412(b)(5) of the SDWA, EPA concluded                   criterion.                                             could have on public trust of utilities.
                                       that the existing MCL was justified. EPA                J. Public Notice Requirements                             EPA agrees on the importance of
                                       will review the bromate MCL as part of                                                                         addressing possible reproductive and
                                                                                               1. Today’s Rule
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                                       the six-year review process and                                                                                developmental health risks. However,
                                       determine whether the MCL should                          Today’s rule does not alter existing                 given the uncertainties in the science
                                       remain at 0.010 mg/L or be reduced to                   public notification language for TTHM,                 and our lack of knowledge of how to
                                       a lower level. As a part of that review,                HAA5 or TOC, which are listed under                    best communicate undefined risks, a
                                       EPA will consider the increased                         40 CFR 141.201–141.210 (Subpart Q).                    general statement about reproductive

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                                       434                      Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                       and developmental health effects is                                          exemptions in accordance with section                           EPA has determined that affordable
                                       premature at this time. The Agency                                           1416(a) of the SDWA and EPA’s                                   compliance technologies are available.
                                       needs to understand how best to                                              regulations.                                                       The 1996 Amendments to the SDWA
                                       characterize and communicate these                                                                                                           identify three categories of small public
                                       risks and what to do to follow up any                                        2. Background and Analysis                                      water systems that need to be addressed:
                                       such communication. The public                                                  a. Variances. The SDWA provides for                          (1) Those serving a population of 3301–
                                       deserves accurate, timely, relevant, and                                     two types of variances—general                                  10,000; (2) those serving a population of
                                       understandable communication. The                                            variances and small system variances.                           500–3300; and (3) those serving a
                                       Agency will continue to follow up on                                         Under section 1415(a)(1)(A) of the                              population of 25–499. The SDWA
                                       this issue with additional research,                                         SDWA, a State that has primary                                  requires EPA to make determinations of
                                       possibly including a project to work                                         enforcement responsibility (primacy), or                        available compliance technologies for
                                       with stakeholders to assess risk                                             EPA as the primacy agency, may grant                            each size category. A compliance
                                       communication strategies.                                                    general variances from MCLs to those                            technology is a technology that is
                                          Some comments also suggested                                                                                                              affordable and that achieves compliance
                                                                                                                    public water systems of any size that
                                       leaving the choice of language up to the                                                                                                     with the MCL and/or treatment
                                                                                                                    cannot comply with the MCLs because
                                       water server. EPA believes that this                                                                                                         technique. Compliance technologies can
                                                                                                                    of characteristics of the raw water
                                       strategy would cause undue confusion                                                                                                         include point-of-entry or point-of-use
                                                                                                                    sources. The primacy agency may grant
                                       to both the PWS and the public.                                                                                                              treatment units. Variance technologies
                                          Commenters generally agreed that                                          general variances to a system on
                                                                                                                    condition that the system install the best                      are only specified for those system size/
                                       both wholesale and consecutive systems                                                                                                       source water quality combinations for
                                       that conduct monitoring be required to                                       technology, treatment techniques, or
                                                                                                                                                                                    which there are no listed affordable
                                       report their own analytical results as                                       other means that EPA finds available
                                                                                                                                                                                    compliance technologies.
                                       part of their CCRs. One commenter                                            and based upon an evaluation
                                                                                                                                                                                       Using its current National
                                       requested clarification of consecutive                                       satisfactory to the State that indicates
                                                                                                                                                                                    Affordability Criteria, EPA has
                                       system public notification requirements                                      that alternative sources of water are not
                                                                                                                                                                                    determined that multiple affordable
                                       when there is a violation in the                                             reasonably available to the system. At
                                                                                                                                                                                    compliance technologies are available
                                       wholesale system but the consecutive                                         the time this type of variance is granted,
                                                                                                                                                                                    for each of the three system sizes
                                       system data indicate that it meets DBP                                       the State must prescribe a compliance
                                                                                                                                                                                    (USEPA 2005a), and therefore did not
                                       MCLs.                                                                        schedule and may require the system to
                                                                                                                                                                                    identify any variance treatment
                                          Although EPA requires consecutive                                         implement additional control measures.
                                                                                                                                                                                    technologies. The analysis was
                                       systems to conduct appropriate public                                        Furthermore, before EPA or the State
                                                                                                                                                                                    consistent with the current methodology
                                       notification of violations (whether in the                                   may grant a general variance, it must
                                                                                                                                                                                    used in the document ‘‘National-Level
                                       wholesale or consecutive system), there                                      find that the variance will not result in
                                                                                                                                                                                    Affordability Criteria Under the 1996
                                       may be cases where the violation may                                         an unreasonable risk to health (URTH)                           Amendments to the Safe Drinking Water
                                       only affect an isolated portion of the                                       to the public served by the public water                        Act’’ (USEPA 1998d) and the ‘‘Variance
                                       distribution system. Under the public                                        system. In today’s final rule, EPA is                           Technology Findings for Contaminants
                                       notification rule, the State may allow                                       specifying BATs for general variances                           Regulated Before 1996’’ (USEPA 1998e).
                                       systems to limit distribution of the                                         under section 1415(a) (see section IV.D).                       However, EPA is currently reevaluating
                                       notice to the area that is out of                                               Section 1415(e) authorizes the                               its national-level affordability criteria
                                       compliance if the system can                                                 primacy agency to issue variances to                            and has solicited recommendations
                                       demonstrate that the violation occurred                                      small public water systems (those                               from both the NDWAC and the SAB as
                                       in a part of the distribution system that                                    serving fewer than 10,000 people) where                         part of this review. EPA intends to
                                       is ‘‘physically or hydraulically isolated                                    the primacy agent determines (1) that                           apply the revised criteria to the Stage 2
                                       from other parts of the distribution                                         the system cannot afford to comply with                         DBPR once they have been finalized for
                                       system.’’ This provision remains in                                          an MCL or treatment technique and (2)                           the purpose of determining whether to
                                       place. As for a consecutive system                                           that the terms of the variances will                            enable States to give variances. Thus,
                                       whose wholesale system is in violation,                                      ensure adequate protection of human                             while the analysis of Stage 2 household
                                       the consecutive system is not required                                       health (63 FR 43833, August 14, 1998)                           costs will not change, EPA’s
                                       to conduct public notification if DBP                                        (USEPA 1998c). These variances may                              determination regarding the availability
                                       levels in the consecutive system are in                                      only be granted where EPA has                                   of affordable compliance technologies
                                       compliance.                                                                  determined that there is no affordable                          for the different categories of small
                                       K. Variances and Exemptions                                                  compliance technology and has                                   systems may.
                                                                                                                    identified a small system variance                                 b. Affordable Treatment Technologies
                                       1. Today’s Rule                                                              technology under section 1412(b)(15) for                        for Small Systems. The treatment trains
                                          States may grant variances in                                             the contaminant, system size and source                         considered and predicted to be used in
                                       accordance with sections 1415(a) and                                         water quality in question. As discussed                         EPA’s compliance forecast for systems
                                       1415(e) of the SDWA and EPA’s                                                below, small system variances under                             serving under 10,000 people, are listed
                                       regulations. States may grant                                                section 1415(e) are not available because                       in Table IV.K–1.

                                                                                 SW Water Plants                                                                                      GW Water Plants
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                                       •   Switching to chloramines as a residual disinfectant .............................                              •   Switching to chloramines as a residual disinfectant
                                       •   Chlorine dioxide (not for systems serving fewer than 100 people) ......                                        •   UV
                                       •   UV .........................................................................................................   •   Ozone (not for systems serving fewer than 100 people)
                                       •   Ozone (not for systems serving fewer than 100 people) .....................                                    •   GAC20
                                       •   Micro-filtration/Ultra-filtration .................................................................            •   Nanofiltration

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                                                                 Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                                              435

                                                                             SW Water Plants                                                                            GW Water Plants

                                       • GAC20.
                                       • GAC20 + Advanced disinfectants.
                                       • Integrated Membranes.
                                          Note: Italicized technologies are those predicted to be used in the compliance forecast.
                                          Source: Exhibits 5.11b and 5.14b, USEPA 2005a.

                                          The household costs for these                                  systems under the Stage 2 DBPR will be                      schedule or use excessive capacity to
                                       technologies were compared against the                            the same as under the Stage 1 DBPR                          avoid installing a costly technology to
                                       EPA’s current national-level                                      (because many systems serving fewer                         comply with the Stage 2 DBPR. The
                                       affordability criteria to determine the                           than 500 people will have the same                          system also may identify another water
                                       affordable treatment technologies. The                            single sampling site under both rules);                     source that has lower TTHM and HAA5
                                       Agency’s national level affordability                             these systems will have already                             precursor levels. Systems that can
                                       criteria were published in the August 6,                          installed the necessary compliance                          identify such an alternate water source
                                       1998 Federal Register (USEPA 1998d).                              technology to comply with the Stage 1                       may not have to treat that new source
                                       A complete description of how this                                DBPR. It is also possible that less costly                  water as intensely as their current
                                       analysis was applied to Stage 2 DBPR is                           technologies such as those for which                        source, resulting in lower treatment
                                       given in Section 8.3 of the Economic                              percentage use caps were set in the                         costs. Systems may elect to connect to
                                       Analysis (USEPA 2005a).                                           decision tree may actually be used to                       a neighboring water system. While
                                          Of the technologies listed in Table                            achieve compliance (e.g., chloramines,
                                       IV.K–1, integrated membranes with                                                                                             connecting to another system may not
                                                                                                         UV). Thus, EPA believes that                                be feasible for some remote systems,
                                       chloramines, GAC20 with advanced                                  compliance by these systems will be
                                       oxidants, and ozone are above the                                                                                             EPA estimates that more than 22 percent
                                       affordability threshold in the 0 to 500                              As shown in Table IV.K–2, the cost                       of all small water systems are located
                                       category. No treatment technologies are                           model predicts that some households                         within metropolitan regions (USEPA
                                       above the affordability threshold in the                          served by very small systems will                           2000f) where distances between
                                       500 to 3,300 category or the 3,300 to                             experience household cost increases                         neighboring systems will not present a
                                       10,000 category. As shown in the                                  greater than the available expenditure                      prohibitive barrier. Low-cost
                                       Economic Analysis for systems serving                             margins as a result of adding advanced                      alternatives to reduce total
                                       fewer than 500 people, 14 systems are                             technology for the Stage 2 DBPR                             trihalomethanes (TTHM) and haloacetic
                                       predicted to use GAC20 with advanced                              (USEPA 2005a). This prediction may be                       acid (HAA5) levels also include
                                       disinfectants, one system is predicted to                         overestimated because small systems                         distribution system modifications such
                                       use integrated membranes, and no                                  may have other compliance alternatives                      as flushing distribution mains more
                                       systems are predicted to use ozone to                             available to them besides adding                            frequently, looping to prevent dead
                                       comply with the Stage 2 DBPR (USEPA                               treatment, which were not considered in                     ends, and optimizing storage to
                                       2005a). However, several alternate                                the model. For example, some of these                       minimize retention time. More
                                       technologies are affordable and likely                            systems currently may be operated on a                      discussion of household cost increases
                                       available to these systems. In some                               part-time basis; therefore, they may be                     is presented in Section VI.E and the
                                       cases, the compliance data for these                              able to modify the current operational                      Economic Analysis (USEPA 2005a).
                                                                   Number of                                                                                                      Number of
                                                                                                                                                                   Number of                     Number of      Total num-
                                                                  households                                                                                                       surface
                                                                                                                                                                  households                    groundwater    ber of plants
                                                                   served by                                                                                                     water plants
                                                                                                                                                                  with annual                    plants with   with annual
                                                                  plants add-                                      90th Per-       95th Per-                                     with annual
                                                                                  Mean an-        Median an-                                        Available       cost in-                    annual cost       cost in-
                                         Systems size               ing treat-                                     centile an-     centile an-                                     cost in-
                                                                                 nual house-      nual house-                                      expenditure      creases                      increases        creases
                                          (population              ment (Per-                                     nual house-     nual house-                                      creases
                                                                                 hold cost in-    hold cost in-                                     margin ($/    greater than                  greater than   greater than
                                            seved)                 cent of all                                    hold cost in-   hold cost in-                                  greater than
                                                                                    crease           crease                                           hh/yr)       the avail-                     the avail-     the avail-
                                                                  households                                         crease          crease                                       the avail-
                                                                                                                                                                    able ex-                       able ex-       able ex-
                                                                   subject to                                                                                                      able ex-
                                                                                                                                                                   penditure                      penditure      penditure
                                                                  the Stage 2                                                                                                     penditure
                                                                                                                                                                     margin                        margin         margin
                                                                     DBPR)                                                                                                          margin
                                                                       A               B               C               D               E               F               G              H              I          J=H+I
                                       0–500 ................        43045(3)         $201.55         $299.01         $299.01         $414.74              $733            964            15              0              15
                                       501–3,300 .........         205842 (4)          $58.41          $29.96          $75.09         $366.53              $724              0             9              0               0
                                       3,301–10,000 ....           342525 (5)          $37.05          $14.59          $55.25         $200.05              $750              0             0              0               0
                                         Notes: Household unit costs represent treatment costs only. All values in year 2003 dollars.
                                         Source: Exhibit 8.4c, USEPA 2005a.

                                          c. Exemptions. Under section 1416(a),                          such as qualification of the PWS as                         effective date of the NPDWR, or for a
                                       EPA or a State that has primary                                   serving a disadvantaged community),                         system that was not in operation by that
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                                       enforcement responsibility (primacy)                              the PWS is unable to comply with the                        date, only if no reasonable alternative
                                       may exempt a public water system from                             requirement or implement measures to                        source of drinking water is available to
                                       any requirements related to an MCL or                             develop an alternative source of water                      the new system; and (4) management or
                                       treatment technique of an NPDWR, if it                            supply; (2) the exemption will not result                   restructuring changes (or both) cannot
                                       finds that (1) due to compelling factors                          in an unreasonable risk to health; and;                     reasonably result in compliance with
                                       (which may include economic factors                               (3) the PWS was in operation on the                         the Act or improve the quality of

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                                       436               Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                       drinking water. If EPA or the State                     to recognize and respond to problems.                  recommended Stage 2 compliance
                                       grants an exemption to a public water                   Subpart H systems were required to be                  monitoring sites as part of the IDSE
                                       system, it must at the same time                        operated by qualified operators under                  report.
                                       prescribe a schedule for compliance                     the SWTR (§ 141.70). The Stage 1 DBPR                    Systems must report compliance with
                                       (including increments of progress or                    added requirements for all disinfected                 Stage 2 TTHM and HAA5 MCLs (0.080
                                       measures to develop an alternative                      systems to be operated by qualified                    mg/LTTHM and 0.060 mg/L HAA5, as
                                       source of water supply) and                             personnel who meet the requirements                    LRAAs) according to the schedules
                                       implementation of appropriate control                   specified by the State, which may differ               specified in §§ 141.620 and 141.629 and
                                       measures that the State requires the                    based on system size and type. The rule                discussed in section IV.E of today’s
                                       system to meet while the exemption is                   also requires that States maintain a                   preamble. Reporting for DBP
                                       in effect. Under section 1416(b)(2)(A),                 register of qualified operators (40 CFR                monitoring, as described previously,
                                       the schedule prescribed shall require                   141.130(c)). While the Stage 2 DBPR                    will remain generally consistent with
                                       compliance as expeditiously as                          requirements do not supercede or                       current public water system reporting
                                       practicable (to be determined by the                    modify the requirement that disinfected                requirements (§ 141.31 and § 141.134);
                                       State), but no later than 3 years after the             systems be operated by qualified                       systems will be required to calculate
                                       effective date for the regulations                      operators, such personnel play an                      and report each LRAA (instead of the
                                       established pursuant to section                         important role in delivering drinking                  system’s RAA) and each individual
                                       1412(b)(10). For public water systems                   water that meets Stage 2 MCLs to the                   monitoring result (as required under the
                                       which do not serve more than a                          public. States should also review and                  Stage 1 DBPR). Systems will also be
                                       population of 3,300 and which need                      modify, as required, their qualification               required to provide a report to the State
                                       financial assistance for the necessary                  standards to take into account new                     about each operational evaluation
                                       improvements, EPA or the State may                      technologies (e.g., ultraviolet (UV)                   within 90 days, as discussed in section
                                       renew an exemption for one or more                      disinfection) and new compliance                       IV.H. Reports and evaluations must be
                                       additional two-year periods, but not to                 requirements (including simultaneous                   kept for 10 years and may prove
                                       exceed a total of 6 years, if the system                compliance and consecutive system                      valuable in identifying trends and
                                       establishes that it is taking all                       requirements). EPA received only one                   recurring issues.
                                       practicable steps to meet the                           comment on this topic; the commenter
                                       requirements above. A public water                                                                             2. Summary of Major Comments
                                                                                               supported the need for a qualified
                                       system shall not be granted an                          operator.                                                 EPA requested comment on all system
                                       exemption unless it can establish that                                                                         reporting and recordkeeping
                                       either: (1) the system cannot meet the                  M. System Reporting and Recordkeeping                  requirements. Commenters generally
                                       standard without capital improvements                   Requirements                                           supported EPA’s proposed
                                       that cannot be completed prior to the                   1. Today’s Rule                                        requirements, but expressed concern
                                       date established pursuant to section                                                                           about two specific issues. The first issue
                                       1412(b)(10); (2) in the case of a system                   Today’s Stage 2 DBPR, consistent
                                                                                               with the existing system reporting and                 was the data management and tracking
                                       that needs financial assistance for the                                                                        difficulties that States would face if EPA
                                       necessary implementation, the system                    recordkeeping regulations under 40 CFR
                                                                                               141.134 (Stage 1 DBPR), requires public                finalized a monitoring approach which
                                       has entered into an agreement to obtain                                                                        had both plant-based and population-
                                       financial assistance pursuant to section                water systems (including consecutive
                                                                                               systems) to report monitoring data to                  based requirements, as was proposed.
                                       1452 or any other Federal or state                                                                             Since today’s rule contains only
                                       program; or (3) the system has entered                  States within ten days after the end of
                                                                                               the compliance period. In addition,                    population-based monitoring
                                       into an enforceable agreement to                                                                               requirements, this concern is no longer
                                       become part of a regional public water                  systems are required to submit the data
                                                                                               required in § 141.134. These data are                  an issue. See section IV.G in today’s
                                       system.                                                                                                        preamble for further discussion.
                                                                                               required to be submitted quarterly for
                                       3. Summary of Major Comments                            any monitoring conducted quarterly or                     The second concern related to
                                                                                               more frequently, and within ten days of                reporting associated with the IDSE.
                                          Several commenters agreed with the                                                                          Commenters who supported an
                                       proposal not to list variances                          the end of the monitoring period for less
                                                                                               frequent monitoring. As with other                     approach other than the IDSE for
                                       technologies for the Stage 2 DBPR. One                                                                         determining Stage 2 compliance
                                       commenter requested that EPA modify                     chemical analysis data, the system must
                                                                                               keep the results for 10 years.                         monitoring locations did not support
                                       the methodology used to assess                                                                                 IDSE-related reporting. The IDSE
                                       affordability. As mentioned earlier, EPA                   In addition to the existing Stage 1
                                                                                               reporting requirements, today’s rule                   remains a key component of the final
                                       is currently reevaluating its national-                                                                        rule; thus, EPA has retained IDSE-
                                       level affordability criteria and has                    requires systems to perform specific
                                                                                               IDSE-related reporting to the primacy                  related reporting. However, the Agency
                                       solicited recommendations from both                                                                            has modified both the content and the
                                       the NDWAC and the SAB as part of this                   agency, except for systems serving fewer
                                                                                               than 500 for which the State or primacy                timing of the reporting to reduce the
                                       review. EPA intends to apply the                                                                               burden. See sections IV.F and IV.E,
                                       revised criteria to the Stage 2 DBPR for                agency has waived this requirement.
                                                                                               Required reporting includes submission                 respectively, of today’s preamble for
                                       the purpose of determining whether to                                                                          further discussion.
                                       enable States to give variances.                        of IDSE monitoring plans, 40/30
                                                                                               certification, and IDSE reports. This                  N. Approval of Additional Analytical
                                       L. Requirements for Systems to Use                      reporting must be accomplished on the                  Methods
                                       Qualified Operators                                     schedule specified in the rule (see
                                          EPA believes that systems that must                  § 141.600(c)) and discussed in section                 1. Today’s Rule
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                                       make treatment changes to comply with                   IV.E of today’s preamble. System                         EPA is taking final action to:
                                       requirements to reduce microbiological                  submissions must include the elements                    (1) allow the use of 13 methods
                                       risks and risks from disinfectants and                  identified in subpart U and discussed                  published by the Standard Methods
                                       disinfection byproducts should be                       further in section IV.F of today’s                     Committee in Standard Methods for the
                                       operated by personnel who are qualified                 preamble. These elements include                       Examination of Water and Wastewater,

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                                                              Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                                                                              437

                                       20th edition, 1998 (APHA 1998) and 12                                    sample preservation; and require that                                         changes in the same sections of the CFR.
                                       methods in Standard Methods Online.                                      TOC samples be preserved at the time                                          EPA decided to make all the changes to
                                         (2) approve three methods published                                    of collection.                                                                § 141.131 as part of the Stage 2 DBPR
                                       by American Society for Testing and                                        (7) clarify which methods are                                               and the remainder of the methods that
                                       Materials International.                                                 approved for magnesium hardness                                               were proposed with the Stage 2 DBPR
                                         (3) approve EPA Method 327.0                                           determinations (40 CFR 141.131 and                                            will be considered as part of the
                                       Revision 1.1 (USEPA 2005h) for daily                                     141.135).                                                                     Methods Update Rule, which will be
                                       monitoring of chlorine dioxide and                                                                                                                     finalized at a later date. Two ASTM
                                                                                                                2. Background and Analysis
                                       chlorite, EPA Method 552.3 (USEPA                                                                                                                      methods, D 1253–86(96) and D 1253–03,
                                       2003f) for haloacetic acids (five)                                         The Stage 1 Disinfectants and                                               that were proposed in the Methods
                                       (HAA5), EPA Methods 317.0 Revision 2                                     Disinfection Byproducts Rule (Stage 1                                         Update Rule, are being approved for
                                       (USEPA 2001c) and 326.0 (USEPA 2002)                                     DBPR) was promulgated on December                                             measuring chlorine residual as part of
                                       for bromate, chlorite, and bromide, EPA                                  16, 1998 (USEPA 1998a) and it included                                        today’s action.
                                       Method 321.8 (USEPA 2000g) for                                           approved analytical methods for DBPs,                                            Minor corrections have been made in
                                       bromate only, and EPA Method 415.3                                       disinfectants, and DBP precursors.                                            two of the methods that were proposed
                                       Revision 1.1 (USEPA 2005l) for total                                     Additional analytical methods became                                          in the Stage 2 DBPR. In today’s rule, the
                                       organic carbon (TOC) and specific                                        available subsequent to the rule and                                          Agency is approving EPA Method 327.0
                                       ultraviolet absorbance (SUVA).                                           were proposed in the Stage 2                                                  (Revision 1.1, 2005) which corrects
                                         (4) update the citation for EPA                                        Disinfectants and Disinfection                                                three typographical errors in the
                                       Method 300.1 (USEPA 2000h) for                                           Byproducts Rule (Stage 2 DBPR)                                                proposed method.
                                       bromate, chlorite, and bromide.                                          (USEPA 2003a). These methods are                                                 EPA is also approving EPA Method
                                         (5) standardize the HAA5 sample                                        applicable to monitoring that is required                                     415.3 (Revision 1.1, 2005), which does
                                       holding times and the bromate sample                                     under the Stage 1 DBPR. After the Stage                                       not contain the requirement that
                                       preservation procedure and holding                                       2 DBPR proposal, analytical methods for                                       samples for the analysis of TOC must be
                                       time.                                                                    additional drinking water contaminants                                        received within 48 hours of sample
                                         (6) add the requirement to remove                                      were proposed for approval in a                                               collection.
                                       inorganic carbon prior to determining                                    Methods Update Rule proposal (USEPA                                              A summary of the methods that are
                                       TOC or DOC, remove the specification                                     2004). The Stage 2 DBPR and Methods                                           included in today’s rule is presented in
                                       of type of acid used for TOC/DOC                                         Update Rule proposals both included                                           Table IV.N–1.

                                                                                      TABLE IV.N–1. ANALYTICAL METHODS APPROVED IN TODAY’S RULE
                                                                                                                                   Standard methods 20th
                                                     Analyte                                 EPA method                                                                         Standard methods online                              Other

                                                                                                                         § 141.131—Disinfection Byproducts

                                       HAA5 ..................................    552.3 .................................        6251 B ..............................         6251 B–94 ........................
                                       Bromate .............................      317.0, Revision 2.0 ...........                ...........................................   ...........................................   ASTM D 6581–00
                                                                                  321.8 .................................
                                                                                  326.0 .................................
                                       Chlorite (monthly or daily)                317.0, Revision 2.0 ...........                ...........................................   ...........................................   ASTM D 6581–00
                                                                                  326.0 .................................
                                       Chlorite (daily) ....................      327.0, Revision 1.1 ...........                4500–ClO2 E .....................             4500–ClO2 E–00 ...............

                                                                                                                                  § 141.131—Disinfectants

                                       Chlorine (free, combined,                  ...........................................    4500–Cl D .........................           4500–Cl D–00 ...................              ASTM D 1253–86(96)
                                         total).                                                                                 4500–Cl F .........................           4500–Cl F–00 ...................              ASTM D 1253–03
                                                                                                                                 4500–Cl G .........................           4500–Cl G–00 ...................
                                       Chlorine (total) ...................       ...........................................    4500–Cl E .........................           4500–Cl E–00 ...................
                                                                                                                                 4500–Cl I ..........................          4500–Cl I–00 ....................
                                       Chlorine (free) ....................       ...........................................    4500–Cl H .........................           4500–Cl H–00 ...................
                                       Chlorine Dioxide ................          327.0, Revision 1.1 ...........                4500–ClO2 D .....................             4500–ClO2 E–00 ...............
                                                                                                                                 4500–ClO2 E .....................

                                                                                                                                § 141.131—Other parameters

                                       Bromide ..............................     317.0, Revision 2.0 ...........                ...........................................   ...........................................   ASTM D 6581–00
                                                                                  326.0 .................................
                                       TOC/DOC ..........................         415.3, Revision 1.1 ...........                5310 B ..............................         5310 B–00 ........................
                                                                                                                                 5310 C ..............................         5310 C–00 ........................
                                                                                                                                 5310 D ..............................         5310 D–00 ........................
                                       UV254 ..................................   415.3, Revision 1.1 ...........                5910 B ..............................         5910 B–00 ........................
                                       SUVA .................................     415.3, Revision 1.1 ...........                ...........................................   ...........................................
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                                       438                     Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                       O. Laboratory Certification and                                            analyses to be conducted by approved                           PE acceptance criteria will be subject to
                                       Approval                                                                   parties. It revises the acceptance criteria                    the new criteria when it is time for them
                                       1. PE Acceptance Criteria                                                  for performance evaluation (PE) studies                        to analyze their annual DBP PE
                                                                                                                  which laboratories must pass as part of                        sample(s). Today’s rule also requires
                                          a. Today’s rule. Today’s rule                                           the certification program. The new                             that TTHM and HAA5 analyses that are
                                       maintains the requirements of                                              acceptance limits are effective 60 days                        performed for the IDSE or system-
                                       laboratory certification for laboratories
                                                                                                                  after promulgation. Laboratories that                          specific study be conducted by
                                       performing analyses to demonstrate
                                                                                                                  were certified under the Stage 1 DBPR                          laboratories certified for those analyses.
                                       compliance with MCLs and all other

                                                                                  TABLE IV.O–1.—PERFORMANCE EVALUATION (PE) ACCEPTANCE CRITERIA
                                                                                                                                              limits (per-
                                                                                    DBP                                                                                                    Comments
                                                                                                                                              cent of true

                                          Chloroform .............................................................................                      ±20   Laboratory must meet all 4 individual THM acceptance limits in
                                                                                                                                                                order to successfully pass a PE sample for TTHM
                                          Bromodichloromethane .........................................................                                ±20
                                          Dibromochloromethane .........................................................                                ±20
                                          Bromoform .............................................................................                       ±20
                                          Monochloroacetic Acid ..........................................................                              ±40   Laboratory must meet the acceptance limits for 4 out of 5 of the
                                                                                                                                                                HAA5 compounds in order to successfully pass a PE sample
                                                                                                                                                                for HAA5
                                           Dichloroacetic Acid ................................................................                         ±40
                                           Trichloroacetic Acid ...............................................................                         ±40
                                           Monobromoacetic Acid ..........................................................                              ±40
                                           Dibromoacetic Acid ...............................................................                           ±40
                                       Chlorite .........................................................................................               ±30
                                       Bromate ........................................................................................                 ±30

                                          b. Background and analysis. The Stage                                   DBP in the PE studies, so that                                 confusion, EPA has modified the rule
                                       1 DBPR (USEPA 1998a) specified that in                                     laboratories would not be required to                          language to allow laboratories one year
                                       order to be certified the laboratory must                                  meet tighter criteria in the PE study than                     from today’s date to meet the new PE
                                       pass an annual performance evaluation                                      they are required to meet with the                             criteria.
                                       (PE) sample approved by EPA or the                                         minimum reporting level (MRL) check
                                       State using each method for which the                                      standard. EPA has addressed this                               2. Minimum Reporting Limits
                                       laboratory wishes to maintain                                              concern by directing the PE sample                               a. Today’s rule. EPA is establishing
                                       certification. The acceptance criteria for                                 suppliers to use concentrations no less                        regulatory minimum reporting limits
                                       the DBP PE samples were set as                                             than 10 µg/L for the individual THM
                                                                                                                                                                                 (MRLs) for compliance reporting of
                                       statistical limits based on the                                            and HAAs, 100 µg/L for chlorite, and 7
                                                                                                                                                                                 DBPs by Public Water Systems. These
                                       performance of the laboratories in each                                    µg/L for bromate in PE studies used for
                                                                                                                                                                                 regulatory MRLs (Table IV.O–2) also
                                       study. This was done because EPA did                                       certifying drinking water laboratories.
                                       not have enough data to specify fixed                                         Two commenters requested that the                           define the minimum concentrations that
                                       acceptance limits.                                                         effective date for the new PE acceptance                       must be reported as part of the
                                          Subsequent to promulgation of the                                       criteria be extended from 60 days to 180                       Consumer Confidence Reports (40 CFR
                                       Stage 1 DBPR, EPA was able to evaluate                                     days, because they felt that 60 days was                       § 141.151(d)). EPA is incorporating
                                       data from PE studies conducted during                                      not enough time for laboratories to meet                       MRLs into the laboratory certification
                                       the Information Collection Rule (USEPA                                     the new criteria. EPA realized from                            program for DBPs by requiring
                                       1996) and during the last five general                                     those comments that the original intent                        laboratories to include a standard near
                                       Water Supply PE studies. Based on the                                      of the proposal was not clearly                                the MRL concentration as part of the
                                       evaluation process as described in the                                     explained; the 60 days was to be the                           calibration curve for each DBP and to
                                       proposed Stage 2 DBPR (USEPA 2003a),                                       deadline for when the PE providers                             verify the accuracy of the calibration
                                       EPA determined that fixed acceptance                                       must change the acceptance criteria that                       curve at the MRL concentration by
                                       limits could be established for the DBPs.                                  are used when the studies are                                  analyzing an MRL check standard with
                                       Today’s action replaces the statistical PE                                 conducted. Laboratories would have to                          a concentration less than or equal to
                                       acceptance limits with fixed limits                                        meet the criteria when it is time for                          110% of the MRL with each batch of
                                       effective one year after promulgation.                                     them to analyze their annual PE samples                        samples. The measured DBP
                                          c. Summary of major comments. Four                                      in order to maintain certification.                            concentration for the MRL check
                                       commenters supported the fixed                                             Depending upon when the last PE                                standard must be ±50% of the expected
                                       acceptance criteria as presented in the                                    sample was analyzed, laboratories could                        value, if any field sample in the batch
                                       proposed rule. One requested that a                                        have up to one year to meet the new                            has a concentration less than 5 times the
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                                       minimum concentration be set for each                                      criteria. In order to eliminate this                           regulatory MRL.

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                                                                                              TABLE IV.O–2.—REGULATORY MINIMUM REPORTING LEVELS
                                                                                                                     Minimum reporting level
                                                                        DBP                                                                                                    Comments
                                                                                                                           (mg/L) 1

                                       TTHM 2
                                           Chloroform ......................................................                           0.0010
                                           Bromodichloromethane ..................................                                     0.0010
                                           Dibromochloromethane ..................................                                     0.0010
                                           Bromoform ......................................................                            0.0010
                                       HAA5 2
                                           Monochloroacetic Acid ...................................                                   0.0020
                                           Dichloroacetic Acid .........................................                               0.0010
                                           Trichloroacetic Acid ........................................                               0.0010
                                           Monobromoacetic Acid ...................................                                    0.0010
                                           Dibromoacetic Acid ........................................                                 0.0010
                                       Chlorite ..................................................................                      0.020    Applicable to monitoring as prescribed in § 141.132(b)(2)(i)(B)
                                                                                                                                                   and (b)(2)(ii).
                                       Bromate .................................................................            0.0050 or 0.0010     Laboratories that use EPA Methods 317.0 Revision 2.0, 326.0 or
                                                                                                                                                   321.8 must meet a 0.0010 mg/L MRL for bromate.
                                          1 The calibration curve must encompass the regulatory minimum reporting level (MRL) concentration. Data may be reported for concentrations
                                       lower than the regulatory MRL as long as the precision and accuracy criteria are met by analyzing an MRL check standard at the lowest report-
                                       ing limit chosen by the laboratory. The laboratory must verify the accuracy of the calibration curve at the MRL concentration by analyzing an
                                       MRL check standard with a concentration less than or equal to 110% of the MRL with each batch of samples. The measured concentration for
                                       the MRL check standard must be ±50% of the expected value, if any field sample in the batch has a concentration less than 5 times the regu-
                                       latory MRL. Method requirements to analyze higher concentration check standards and meet tighter acceptance criteria for them must be met in
                                       addition to the MRL check standard requirement.
                                          2 When adding the individual trihalomethane or haloacetic acid concentrations to calculate the TTHM or HAA5 concentrations, respectively, a
                                       zero is used for any analytical result that is less than the MRL concentration for that DBP, unless otherwise specified by the State.

                                         b. Background and analysis. EPA                                        analyze the MRL check standard, but                   that are no longer effective. These
                                       proposed to establish regulatory MRLs                                    the laboratory is only required to meet               sections have been superceded by new
                                       for DBPs in order to define expectations                                 the accuracy criteria (±50%) if a field               requirements elsewhere in Part 141.
                                       for reporting compliance monitoring                                      sample has a concentration less than                     Sections 141.12 (Maximum
                                       data to the Primacy Agencies and in the                                  five times the regulatory MRL                         contaminant levels for total
                                       Consumer Confidence Reports. The                                         concentration.                                        trihalomethanes) and 141.30 (Total
                                       proposed MRLs were generally based on                                       EPA proposed a regulatory MRL of                   trihalomethanes sampling, analytical
                                       those used during the Information                                        0.200 mg/L for chlorite, because data                 and other requirements) were
                                       Collection Rule (USEPA 1996), because                                    from the Information Collection Rule                  promulgated as part of the 1979 TTHM
                                       an analysis of the quality control data                                  indicated that most samples would                     Rule. These sections have been
                                       set from the Information Collection Rule                                 contain concentrations greater than                   superceded in their entirety by § 141.64
                                       (Fair et al. 2002) indicated that                                        0.200 mg/L (USEPA 2003c). EPA also                    (Maximum contaminant levels for
                                       laboratories are able to provide                                         took comment on a lower MRL of 0.020                  disinfection byproducts) and subpart L
                                       quantitative data down to those                                          mg/L. Commenters were evenly divided                  (Disinfectant Residuals, Disinfection
                                       concentrations.                                                          concerning which regulatory MRL                       Byproducts, and Disinfection Byproduct
                                                                                                                concentration should be adopted in the                Precursors), respectively, as of
                                         EPA also proposed that laboratories                                    final rule. EPA has decided to set the                December 31, 2003. Also, § 141.32
                                       be required to demonstrate ability to                                    chlorite regulatory MRL at 0.020 mg/L                 (Public notification) has been
                                       quantitate at the MRL concentrations by                                  in today’s rule. This decision was based              superceded by subpart Q (Public
                                       analyzing an MRL check standard and                                      on two factors. First, the approved                   Notification of Drinking Water
                                       meeting accuracy criteria on each day                                    analytical methods for determining                    Violations), which is now fully in effect.
                                       that compliance samples are analyzed.                                    compliance with the chlorite MCL can                     Section 553 of the Administrative
                                       Three public commenters noted that                                       easily support an MRL of 0.020 mg/L.                  Procedure Act, 5 U.S.C. 553(b)(B),
                                       meeting the accuracy requirement for                                     More importantly, since the proposal,                 provides that, when an agency for good
                                       the MRL check standard did not                                           EPA has learned that water systems that               cause finds that notice and public
                                       contribute to the quality of the data in                                 have low chlorite concentrations in                   procedure are impracticable,
                                       cases in which the concentration of a                                    their water have been obtaining data on               unnecessary, or contrary to the public
                                       DBP in the samples was much higher                                       these low concentrations from their                   interest, the agency may issue a rule
                                       than the MRL. For example, if                                            laboratories and have been using these                without providing prior notice and an
                                       chloroform concentrations are always                                     data in their Consumer Confidence                     opportunity for public comment. In
                                       greater than 0.040 mg/L in a water                                       Reports. Setting the MRL at 0.020 mg/                 addition to updating methods, this rule
                                       system’s samples, then verifying                                         L is reflective of current practices in               also makes minor corrections to the
                                       accurate quantitation at 0.0010 mg/L is                                  laboratories and current data                         National Primary Drinking Water
                                       unnecessary and may require the                                          expectations by water systems.                        Regulations, specifically the Public
                                       laboratory to dilute samples or maintain                                    c. Summary of major comments.                      Notification tables (Subpart Q,
                                       two calibration curves in order to                                       There were no major comments.                         Appendices A and B). Two final
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                                       comply with the requirement. EPA has                                                                                           drinking water rules (66 FR 6976 and 65
                                       taken this into consideration in today’s                                 P. Other Regulatory Changes                           FR 76708) inadvertently added new
                                       rule and has adjusted the requirement                                      As part of today’s action, EPA has                  endnotes to two existing tables using the
                                       accordingly. EPA is maintaining the                                      included several ‘‘housekeeping’’                     same endnote numbers. This rule
                                       requirement for all laboratories to                                      actions to remove sections of Part 141                corrects this technical drafting error by

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                                       renumbering the endnote citations in                    case basis, if a State will use the                    enforcement; (3) keeping records and
                                       these two tables. Thus, additional notice               authority to modify monitoring                         making reports available on activities
                                       and public comment is not necessary.                    requirements under this special primacy                that EPA requires by regulation; (4)
                                       EPA finds that this constitutes ‘‘good                  condition.                                             issuing variances and exemptions (if
                                       cause’’ under 5 U.S.C. 553(b)(B). For the                                                                      allowed by the State), under conditions
                                                                                               2. State Recordkeeping Requirements                    no less stringent than allowed under
                                       same reasons, EPA is making this rule
                                       change effective upon publication. 5                       Today’s rule requires States to keep                SDWA; and (5) adopting and being
                                       U.S.C. 553(d)(3).                                       additional records of the following,                   capable of implementing an adequate
                                                                                               including all supporting information                   plan for the provisions of safe drinking
                                       V. State Implementation                                 and an explanation of the technical                    water under emergency situations.
                                       A. Today’s Rule                                         basis for each decision:                                  40 CFR part 142 sets out the specific
                                                                                                  —very small system waivers.                         program implementation requirements
                                         This section describes the regulations                                                                       for States to obtain primacy for the
                                                                                                  —IDSE monitoring plans.
                                       and other procedures and policies States                                                                       public water supply supervision
                                                                                                  —IDSE reports and 40/30
                                       must adopt to implement today’s rule.                                                                          program as authorized under SDWA
                                                                                                    certifications, plus any
                                       States must continue to meet all other                                                                         section 1413. In addition to adopting
                                                                                                    modifications required by the State.
                                       conditions of primacy in 40 CFR Part                       —operational evaluations conducted                  basic primacy requirements specified in
                                       142. To implement the Stage 2 DBPR,                          by the system.                                    40 CFR Part 142, States may be required
                                       States must adopt revisions to the                                                                             to adopt special primacy provisions
                                       following:                                              3. State Reporting Requirements                        pertaining to specific regulations where
                                         —§ 141.2—Definitions                                     Today’s rule has no new State                       implementation of the rule involves
                                         —§ 141.33—Record maintenance;                         reporting requirements.                                activities beyond general primacy
                                         —§ 141.64—Maximum contaminant                                                                                provisions. States must include these
                                            levels for disinfection byproducts;                4. Interim Primacy
                                                                                                                                                      regulation specific provisions in an
                                         —subpart L—Disinfectant Residuals,                       States that have primacy for every                  application for approval of their
                                            Disinfection Byproducts, and                       existing NPDWR already in effect may                   program revision.
                                            Disinfection Byproduct Precursors;                 obtain interim primacy for this rule,                     The current regulations in 40 CFR
                                         —subpart O, Consumer Confidence                       beginning on the date that the State                   142.14 require States with primacy to
                                            Reports;                                           submits the application for this rule to               keep various records, including the
                                         —subpart Q, Public Notification of                    USEPA, or the effective date of its                    following: analytical results to
                                            Drinking Water Violations;                         revised regulations, whichever is later.               determine compliance with MCLs,
                                         —new subpart U, Initial Distribution                  A State that wishes to obtain interim                  MRDLs, and treatment technique
                                            System Evaluation; and                             primacy for future NPDWRs must obtain                  requirements; PWS inventories; State
                                         —new subpart V, Stage 2 Disinfection                  primacy for today’s rule. As described                 approvals; enforcement actions; and the
                                            Byproducts Requirements.                           in Section IV.F, EPA expects to work                   issuance of variances and exemptions.
                                       1. State Primacy Requirements for                       with States to oversee the individual                  Today’s final rule requires States to
                                       Implementation Flexibility                              distribution system evaluation process                 keep additional records, including all
                                                                                               that begins shortly after rule                         supporting information and an
                                         In addition to adopting basic primacy                 promulgation.                                          explanation of the technical basis for
                                       requirements specified in 40 CFR part                                                                          decisions made by the State regarding
                                       142, States are required to address                     5. IDSE Implementation
                                                                                                                                                      today’s rule requirements. The State
                                       applicable special primacy conditions.                     As discussed in section IV.E, many                  may use these records to identify trends
                                       Special primacy conditions pertain to                   systems will be performing certain IDSE                and determine whether to limit the
                                       specific regulations where                              activities prior to their State receiving              scope of operational evaluations. EPA
                                       implementation of the rule involves                     primacy. During that period, EPA will                  currently requires in 40 CFR 142.15 that
                                       activities beyond general primacy                       act as the primacy agency, but will                    States report to EPA information such as
                                       provisions. The purpose of these special                consult and coordinate with individual                 violations, variance and exemption
                                       primacy requirements in today’s rule is                 States to the extent practicable and to                status, and enforcement actions; today’s
                                       to ensure State flexibility in                          the extent that States are willing and                 rule does not add additional reporting
                                       implementing a regulation that (1)                      able to do so. In addition, prior to                   requirements or modify existing
                                       applies to specific system configurations               primacy, States may be asked to assist                 requirements.
                                       within the particular State and (2) can                 EPA in identifying and confirming                         On April 28, 1998, EPA amended its
                                       be integrated with a State’s existing                   systems that are required to comply                    State primacy regulations at 40 CFR
                                       Public Water Supply Supervision                         with certain IDSE activities. Once the                 142.12 to incorporate the new process
                                       Program. States must include these rule-                State has received primacy, it will                    identified in the 1996 SDWA
                                       distinct provisions in an application for               become responsible for IDSE                            Amendments for granting primary
                                       approval or revision of their program.                  implementation activities.                             enforcement authority to States while
                                       These primacy requirements for                                                                                 their applications to modify their
                                       implementation flexibility are discussed                B. Background and Analysis                             primacy programs are under review (63
                                       in this section.                                           SDWA establishes requirements that a                FR 23362, April 28, 1998) (USEPA
                                         To ensure that a State program                        State or eligible Indian Tribe must meet               1998f). The new process grants interim
                                       includes all the elements necessary for                 to assume and maintain primary                         primary enforcement authority for a
                                       an effective and enforceable program                    enforcement responsibility (primacy) for               new or revised regulation during the
                                       under today’s rule, a State primacy                     its PWSs. These requirements include                   period in which EPA is making a
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                                       application must include a description                  the following activities: (1) Adopting                 determination with regard to primacy
                                       of how the State will implement a                       drinking water regulations that are no                 for that new or revised regulation. This
                                       procedure for modifying consecutive                     less stringent than Federal drinking                   interim enforcement authority begins on
                                       system and wholesale system                             water regulations; (2) adopting and                    the date of the primacy application
                                       monitoring requirements on a case-by-                   implementing adequate procedures for                   submission or the effective date of the

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                                       new or revised State regulation,                        the staggered rule schedule will                       analyses summarized in this section and
                                       whichever is later, and ends when EPA                   facilitate State involvement in pre-                   additional analytical results.
                                       makes a final determination. However,                   primacy implementation.
                                                                                                                                                      A. Regulatory Alternatives Considered
                                       this interim primacy authority is only                     Many commenters also requested that
                                       available to a State that has primacy                   the State have more flexibility to grant                  The Stage 2 DBPR is the second in a
                                       (including interim primacy) for every                   sampling waivers and exemptions. EPA                   set of rules that address public health
                                       existing NPDWR in effect when the new                   believes that it has struck a reasonable               risks from DBPs. EPA promulgated the
                                       regulation is promulgated. States that                  balance among competing objectives in                  Stage 1 DBPR to decrease average
                                       have primacy for every existing NPDWR                   granting State flexibility. State                      exposure to DBPs and mitigate
                                       already in effect may obtain interim                    flexibility comes at a resource cost and               associated health risks—compliance
                                       primacy for this rule and a State that                  excessive system-by-system flexibility                 with TTHM and HAA5 MCLs is based
                                       wishes to obtain interim primacy for                    could overwhelm State resources. Also,                 on averaging concentrations across the
                                       future NPDWRs must obtain primacy for                   EPA believes that much of the                          distribution system. In developing the
                                       this rule.                                              monitoring and water quality                           Stage 2 DBPR, EPA sought to identify
                                          EPA is aware that due to the                         information a State would need to                      and further reduce remaining risks from
                                       complicated wholesale system-                           properly consider whether a waiver is                  exposure to chlorinated DBPs.
                                       consecutive system relationships that                   appropriate is generally not available                    The regulatory options EPA
                                       exist nationally, there will be cases                   and, if available, difficult to evaluate.              considered for the Stage 2 DBPR are the
                                       where the standard monitoring                                                                                  direct result of a consensus rulemaking
                                       framework will be difficult to                          VI. Economic Analysis                                  process (Federal Advisory Committee
                                       implement. Therefore, States may                           This section summarizes the                         Act (FACA) process) that involved
                                       develop, as a special primacy condition,                Economic Analysis for the Final Stage 2                various drinking water stakeholders (see
                                       a program under which the State can                     Disinfectants and Disinfection                         Section III for a description of the FACA
                                       modify monitoring requirements for                      Byproducts Rule (Economic Analysis                     process). The Advisory Committee
                                       consecutive systems. These                              (EA)) (USEPA 2005a). The EA is an                      considered the following key questions
                                       modifications must not undermine                        evaluation of the benefits and costs of                during the negotiation process for the
                                       public health protection and all                        today’s final rule and other regulatory                Stage 2 DBPR:
                                       systems, including consecutive systems,                                                                           • What are the remaining health risks
                                                                                               alternatives the Agency considered.
                                       must comply with the TTHM and HAA5                                                                             after implementation of the Stage 1
                                                                                               Specifically, this evaluation addresses
                                       MCLs based on the LRAA at each                                                                                 DBPR?
                                                                                               both quantified and non-quantified
                                       compliance monitoring location. Each                                                                              • What are approaches to addressing
                                                                                               benefits to PWS consumers, including
                                       consecutive system must have at least                                                                          these risks?
                                                                                               the general population and sensitive                      • What are the risk tradeoffs that need
                                       one compliance monitoring location.                     subpopulations. Costs are presented for
                                       However, such a program allows the                                                                             to be considered in evaluating these
                                                                                               PWSs, States, and consumer                             approaches?
                                       State to establish monitoring
                                                                                               households. Also included is a                            • How do the estimated costs of an
                                       requirements that account for
                                                                                               discussion of potential risks from other               approach compare to reductions in peak
                                       complicated distribution system
                                                                                               contaminants, uncertainties in benefit                 DBP occurrences and overall DBP
                                       relationships, such as where
                                                                                               and cost estimates, and a summary of                   exposure for that approach?
                                       neighboring systems buy from and sell
                                                                                               major comments on the EA for the                          The Advisory Committee considered
                                       to each other regularly throughout the
                                                                                               proposed Stage 2 DBPR.                                 DBP occurrence estimates to be
                                       year, water passes through multiple
                                       consecutive systems before it reaches a                    EPA relied on data from several                     important in understanding the nature
                                       user, or a large group of interconnected                epidemiologic and toxicologic studies,                 of public health risks. Although the ICR
                                       systems have a complicated combined                     the Information Collection Rule (ICR),                 data were collected prior to
                                       distribution system. EPA has developed                  and other sources, along with analytical               promulgation of the Stage 1 DBPR, they
                                       a guidance manual to address these and                  models and input from technical                        were collected under a similar sampling
                                       other consecutive system issues.                        experts, to understand DBP risk,                       strategy. The data support the concept
                                                                                               occurrence, and PWS treatment changes                  that a system could be in compliance
                                       C. Summary of Major Comments                            that will result from today’s rule.                    with the RAA Stage 1 DBPR MCLs of
                                          Public comment generally supported                   Benefits and costs are presented as                    0.080 mg/L and 0.060 mg/L for TTHM
                                       the special primacy requirements in the                 annualized values using social discount                and HAA5, respectively, and yet have
                                       August 11, 2003 proposal, and many                      rates of three and seven percent. The                  points in the distribution system with
                                       commenters expressed appreciation for                   time frame used for benefit and cost                   either periodically or consistently
                                       the flexibility the special primacy                     comparisons is 25 years—approximately                  higher DBP levels.
                                       requirements provided to States.                        five years account for rule                               Based on these findings, the Advisory
                                          Many commenters expressed concern                    implementation and 20 years for the                    Committee discussed an array of
                                       about EPA as the implementer instead                    average useful life of treatment                       alternatives to address disproportionate
                                       of the State, given the existing                        technologies.                                          risk within distribution systems.
                                       relationship between the State and                         EPA has prepared this EA to comply                  Alternative options included lowering
                                       system. EPA agrees that States perform                  with the requirements of SDWA,                         DBP MCLs, revising the method for
                                       an essential role in rule implementation                including the Health Risk Reduction                    MCL compliance determination e.g.,
                                       and intends to work with States to the                  and Cost Analysis required by SDWA                     requiring individual sampling locations
                                       greatest extent possible, consistent with               section 1412(b)(3)(C), and Executive                   to meet the MCL as an LRAA or
                                       the rule schedule promulgated today.                    Order 12866, Regulatory Planning and                   requiring that no samples exceed the
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                                       EPA believes that pre-promulgation                      Review. The full EA is available in the                MCL), and combinations of both. The
                                       coordination with States, changes in the                docket for today’s rule, which is                      Advisory Committee also considered the
                                       final rule strongly supported by States                 available online as described in the                   associated technology changes and costs
                                       (e.g., population-based monitoring                      ADDRESSES section. The full document                   for these alternatives. After narrowing
                                       instead of plant-based monitoring), and                 provides detailed explanations of the                  down options, the Advisory Committee

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                                       primarily focused on four types of                        —MCLs of 0.080 mg/L for TTHM and                     TTHM/HAA5 alternatives described and
                                       alternative MCL scenarios. These are the                    0.060 mg/L for HAA5 as absolute                    the Stage 1 DBPR for a hypothetical
                                       alternatives EPA evaluated in the EA, as                    maximums for individual                            large surface water system. This
                                       follows:                                                    measurements                                       hypothetical system has one treatment
                                       Preferred Alternative                                     —Bromate MCL remaining at 0.010                      plant and measures TTHM in the
                                          —MCLs of 0.080 mg/L for TTHM and                         mg/L                                               distribution system in four locations per
                                            0.060 mg/L for HAA5 as LRAAs                       Alternative 3                                          quarter (the calculation methodology
                                          —Bromate MCL remaining at 0.010                        —MCLs of 0.040 mg/L for TTHM and                     shown would be the same for HAA5).
                                            mg/L                                                   0.030 mg/L for HAA5 as RAAs                        Ultimately, the Advisory Committee
                                       Alternative 1
                                          —MCLs of 0.080 mg/L for TTHM and                       —Bromate MCL remaining at 0.010                      recommended the Preferred Alternative
                                            0.060 mg/L for HAA5 as LRAAs                           mg/L.                                              in combination with an IDSE
                                          —Bromate MCL of 0.005 mg/L                             Figure VI.A–1 shows how compliance                   requirement (discussed in Section IV.F).
                                       Alternative 2                                           would be determined under each of the
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                                       B. Analyses That Support Today’s Final                  predicted pre-Stage 1 baseline, the ICR                Epidemiology, and End Results program
                                       Rule                                                    Matrix Method uses unadjusted ICR                      in conjunction with data from the 2000
                                         EPA’s goals in designing the Stage 2                  TTHM and HAA5 pre-Stage 1 data to                      U.S. Census to estimate the number of
                                       DBPR were to protect public health by                   estimate the percent of plants changing                new bladder cancer cases per year
                                       reducing peak DBP levels in the                         technology to comply with the Stage 2                  (USEPA 2005a). Three approaches were
                                       distribution system while maintaining                   DBPR. EPA gives equal weight to SWAT                   then used to gauge the percentage of
                                       microbial protection. As described                      and ICR Matrix Method predictions in                   cases attributable to DBP exposure (i.e.,
                                                                                               estimating Stage 2 compliance forecasts                population attributable risk (PAR)).
                                       earlier, the Stage 1 DBPR reduces
                                                                                               and resultant reductions in DBP                        Taken together, the three approaches
                                       overall average DBP levels, but specific
                                                                                               exposure. The ICR Matrix Method is                     provide a reasonable estimate of the
                                       locations within distribution systems
                                                                                               also used to estimate reductions in the                range of potential risks. EPA notes that
                                       can still experience relatively high DBP
                                                                                               occurrence of peak TTHM and HAA5                       the existing epidemiological evidence
                                       concentrations. EPA believes that high
                                                                                               concentrations because SWAT-                           has not conclusively established
                                       DBP concentrations should be reduced
                                                                                               predicted TTHM and HAA5                                causality between DBP exposure and
                                       due to the potential association of DBPs
                                                                                               concentrations are valid only when                     any health risk endpoints, so the lower
                                       with cancer, as well as reproductive and
                                                                                               considering national averages, not at the              bound of potential risks may be as low
                                       developmental health effects.
                                                                                               plant level.                                           as zero.
                                         EPA analyzed the benefits and costs                      When evaluating compliance with a
                                       of the four regulatory alternatives                                                                               The first approach used the range of
                                                                                               DBP MCL, EPA assumed that systems
                                       presented in the previous section.                                                                             PAR values derived from consideration
                                                                                               would maintain DBP levels at least 20
                                       Consistent with the recommendations of                                                                         of five individual epidemiology studies.
                                                                                               percent below the MCL. This safety
                                       the Advisory Committee, EPA is                                                                                 This range was used at the basis for the
                                                                                               margin represents the level at which
                                       establishing the preferred alternative to                                                                      Stage 1 and the proposed Stage 2
                                                                                               systems typically take action to ensure
                                       achieve the Agency’s goals for the Stage                                                                       economic analyses (i.e., 2 percent to 17
                                                                                               they meet a drinking water standard and
                                       2 DBPR. The following discussion                                                                               percent) (USEPA 2003a).
                                                                                               reflects industry practice. In addition,
                                       summarizes EPA’s analyses that support                  the safety margin accounts for year-to-                   The second approach used results
                                       today’s final rule. This discussion                     year fluctuations in DBP levels. To                    from the Villanueva et al. (2003) meta-
                                       explains how EPA predicted water                        address the impact of the IDSE, EPA                    analysis. This study develops a
                                       quality and treatment changes,                          also analyzed compliance using a safety                combined Odds Ratio (OR) of 1.2 that
                                       estimated benefits and costs, and                       margin of 25 percent based on an                       reflects the ever-exposed category for
                                       assessed the regulatory alternatives.                   analysis of spatial variability in TTHM                both sexes from all studies considered
                                       1. Predicting Water Quality and                         and HAA5 occurrence. EPA assigned                      in the meta-analysis and yields a PAR
                                       Treatment Changes                                       equal probability to the 20 and 25                     value of approximately 16 percent.
                                                                                               percent safety margin for large and                       The third approach used the
                                          Water quality and treatment data from                medium surface water systems for the                   Villanueva et al. (2004) pooled data
                                       the ICR were used in predicting                         final analysis because both alternatives               analysis to develop a dose-response
                                       treatment plant technology changes (i.e.                are considered equally plausible. EPA                  relationship for OR as a function of
                                       compliance forecasts) and reductions in                 assumes the 20 percent operational                     average TTHM exposure. Using the
                                       DBP exposure resulting from the Stage                   safety margin accounts for variability in              results from this approach, EPA
                                       2 DBPR. Because ICR data were gathered                  small surface water systems and all                    estimates a PAR value of approximately
                                       prior to Stage 1 DBPR compliance                        groundwater systems.                                   17 percent.
                                       deadlines, EPA first accounted for
                                       treatment changes resulting from the                    2. Estimating Benefits                                    EPA used the PAR values from all
                                       Stage 1 DBPR. Benefit and cost                             Quantified benefits estimates for the               three approaches to estimate the number
                                       estimates for the Stage 2 DBPR reflect                  Stage 2 DBPR are based on potential                    of bladder cancer cases ultimately
                                       changes following compliance with the                   reductions in fatal and non-fatal bladder              avoided annually as a result of the Stage
                                       Stage 1 DBPR.                                           cancer cases. In the EA, EPA included                  2 DBPR. To quantify the reduction in
                                          The primary model used to predict                    a sensitivity analysis for benefits from               cases, EPA assumed a linear
                                       changes in treatment and reductions in                  avoiding colon and rectal cancers. EPA                 relationship between average DBP
                                       DBP levels was the Surface Water                        believes additional benefits from this                 concentration and relative risk of
                                       Analytical Tool (SWAT), which EPA                       rule could come from reducing potential                bladder cancer. Because of this, EPA
                                       developed using results from the ICR.                   reproductive and developmental risks.                  considers these estimates to be an upper
                                       SWAT results were applied directly for                  EPA has not included these potential                   bound on the annual reduction in
                                       large and medium surface water systems                  risks in the primary benefit analysis                  bladder cancer cases due to the rule.
                                       and were adjusted for small surface                     because of the associated uncertainty.                    A lag period (i.e., cessation lag) exists
                                       water systems to account for differences                   The major steps in deriving and                     between when reduction in exposure to
                                       in source water DBP precursor levels                    characterizing potential cancer cases                  a carcinogen occurs and when the full
                                       and operational constraints in small                    avoided include the following: (1)                     risk reduction benefit of that exposure
                                       systems. EPA used ICR data and a                        estimate the current and future annual                 reduction is realized by exposed
                                       Delphi poll process (a group of drinking                cases of illness from all causes; (2)                  individuals. No data are available that
                                       water experts who provided best                         estimate how many cases can be                         address the rate of achieving bladder
                                       professional judgment in a structured                   attributed to DBP occurrence and                       cancer benefits resulting from DBP
                                       format) to project technologies selected                exposure; and (3) estimate the reduction               reductions. Consequently, EPA used
                                       by ground water systems.                                in future cases corresponding to                       data from epidemiological studies that
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                                          To address uncertainty in SWAT                       anticipated reductions in DBP                          address exposure reduction to cigarette
                                       predictions, EPA also predicted                         occurrence and exposure due to the                     smoke and arsenic to generate three
                                       treatment changes using a second                        Stage 2 DBPR.                                          possible cessation lag functions for
                                       methodology, called the ‘‘ICR Matrix                       EPA used results from the National                  bladder cancer and DBPs. The cessation
                                       Method.’’ Rather than a SWAT-                           Cancer Institute’s Surveillance,                       lag functions are used in conjunction

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                                       with the rule implementation schedule                   performing these activities and on                     broad spectrum of microbial pathogens,
                                       to project the number of bladder cancer                 laboratory costs.                                      including microorganisms like
                                       cases avoided each year as a result of                     While systems vary with respect to                  Cryptosporidium that are resistant to
                                       the Stage 2 DBPR.                                       many of the input parameters to the                    chlorine.
                                          Although EPA used three approaches                   Stage 2 DBPR cost analysis (e.g., plants                  Alternative 2 would have prohibited
                                       for estimating PAR, for simplicity’s                    per system, population served, flow per                any single sample from exceeding the
                                       sake, EPA used the Villanueva et al.                    population, labor rates), EPA believes                 TTHM or HAA5 MCL. This is
                                       (2003) study to calculate the annual                    that mean values for the various input                 significantly more stringent than the
                                       benefits of the Stage 2 DBPR. The                       parameters are appropriate to generate                 preferred alternative and would likely
                                       benefits estimates derived from                         the best estimate of national costs for                require a large fraction of surface water
                                       Villanueva et al. (2003) capture a                      the rule. Uncertainty in the national                  systems to switch from their current
                                       substantial portion of the overall range                average unit capital and O&M costs for                 treatment practices to more expensive
                                       of results, reflecting the uncertainty in               the various technologies has been                      advanced technologies. Consistent with
                                       both the underlying OR and PAR values,                  incorporated into the cost analysis                    the Advisory Committee, EPA does not
                                       as well as the uncertainty in DBP                       (using Monte Carlo simulation                          believe such a drastic shift is warranted
                                       reductions for Stage 2.                                 procedures). Costs of the Stage 2 DBPR                 at this time.
                                          To assign a monetary value to avoided                are estimated at both mean and 90                         Similarly, Alternative 3, which would
                                       bladder cancer cases, EPA used the                      percent confidence bound values.                       decrease TTHM and HAA5 MCLs to
                                       value of a statistical life (VSL) for fatal                EPA assumes that systems will, to the               0.040 mg/L and 0.030 mg/L,
                                                                                               extent possible, pass cost increases on to             respectively, and would require a
                                       cases and used two alternate estimates
                                                                                               their customers through increases in                   significant portion of surface water
                                       of willingness-to-pay to avoid non-fatal
                                                                                               water rates. Consequently, EPA has also                systems to implement expensive
                                       cases (one based on curable lymphoma
                                                                                               estimated annual household cost                        advanced technologies in place of their
                                       and the other based on chronic
                                                                                               increases for the Stage 2 DBPR. This                   existing treatment. Further, compliance
                                       bronchitis). EPA believes additional
                                                                                               analysis includes costs for all                        with TTHM and HAA5 MCLs under this
                                       benefits from this rule could come from
                                                                                               households served by systems subject to                alternative would be based on the RAA,
                                       a reduction in potential reproductive
                                                                                               the rule, costs just for those households              which does not specifically address DBP
                                       and developmental risks. See Chapter 6
                                                                                               served by systems actually changing                    peaks in the distribution system as the
                                       of the EA for more information on
                                                                                               treatment technologies to comply with                  LRAA, in conjunction with the IDSE,
                                       estimating benefits (USEPA 2005a).                      the rule, costs for households served by               are designed to do. Based on these
                                       3. Estimating Costs                                     small systems, and costs for systems                   considerations, EPA and the Advisory
                                                                                               served by surface water and ground                     Committee did not favor this alternative.
                                          Analyzing costs for systems to comply
                                                                                               water sources.
                                       with the Stage 2 DBPR included                                                                                 C. Benefits of the Stage 2 DBPR
                                       identifying and costing treatment                       4. Comparing Regulatory Alternatives
                                                                                                                                                         The benefits analysis for the Stage 2
                                       process improvements that systems will                     Through the analyses summarized in                  DBPR includes a description of non-
                                       make, as well as estimating the costs to                this section, EPA assessed the benefits                quantified benefits, calculations of
                                       implement the rule, conduct IDSEs,                      and costs of the four regulatory                       quantified benefits, and a discussion of
                                       prepare monitoring plans, perform                       alternatives described previously.                     when benefits will occur after today’s
                                       additional routine monitoring, and                      Succeeding sections of this preamble                   final rule is implemented. An overview
                                       evaluate significant DBP excursion                      present the results of these analyses. As              of the methods used to determine
                                       events. The cost analysis for States/                   recommended by the Advisory                            benefits is provided in Section VI.B.
                                       Primacy Agencies included estimates of                  Committee, EPA is establishing the                     More detail can be found in the final
                                       the labor burdens for training employees                preferred regulatory alternative for                   EA. A summary of benefits for the Stage
                                       on the requirements of the Stage 2                      today’s Stage 2 DBPR. This regulation                  2 DBPR is given in this section.
                                       DBPR, responding to PWS reports, and                    will reduce peak DBP concentrations in
                                       record keeping.                                         distribution systems through requiring                 1. Nonquantified Benefits
                                          All treatment costs are based on mean                compliance determinations with                            Non-quantified benefits of the Stage 2
                                       unit cost estimates for advanced                        existing TTHM and HAA5 MCLs using                      DBPR include potential benefits from
                                       technologies and chloramines.                           the LRAA. Further, the IDSE will ensure                reduced reproductive and
                                       Derivation of unit costs are described in               that systems identify compliance                       developmental risks, reduced risks of
                                       detail in Technologies and Costs for the                monitoring sites that reflect high DBP                 cancers other than bladder cancer, and
                                       Final Long Term 2 Enhanced Surface                      levels. EPA believes that these provision              improved water quality. EPA believes
                                       Water Treatment Rule and Final Stage 2                  are appropriate given the association of               that additional benefits from this rule
                                       Disinfectants and Disinfection                          DBPs with cancer, as well as potential                 could come from a reduction in
                                       Byproducts Rule (USEPA 2005g). Unit                     reproductive and developmental health                  potential reproductive and
                                       costs (capital and O&M) for each of nine                effects.                                               developmental risks. However, EPA
                                       system size categories are calculated                      Alternative 1 would have established                does not believe the available evidence
                                       using mean design and average daily                     the same DBP regulations as the                        provides an adequate basis for
                                       flows values. The unit costs are then                   preferred alternative, and would have                  quantifying these potential risks in the
                                       combined with the predicted number of                   lowered the bromate MCL from 0.010 to                  primary analysis.
                                       plants selecting each technology to                     0.005 mg/L. The Advisory Committee                        Both toxicology and epidemiology
                                       produce national treatment cost                         did not recommend and EPA did not                      studies indicate that other cancers may
                                       estimates.                                              establish this alternative because it                  be associated with DBP exposure but
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                                          Non-treatment costs for                              could have an adverse effect on                        currently there is not enough data to
                                       implementation, the IDSE, monitoring                    microbial protection. The lower bromate                include them in the primary analysis.
                                       plans, additional routine monitoring,                   MCL could cause many systems to                        However, EPA believes that the
                                       and operational evaluations are based                   reduce or eliminate the use of ozone,                  association between exposure to DBPs
                                       on estimates of labor hours for                         which is an effective disinfectant for a               and colon and rectal cancer is possibly

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                                       significant, so an analysis of benefits is              from exposure to chemicals associated                  al. (2003), as described in Section VI.B.
                                       presented as a sensitivity analysis.                    with accidental spills or environmental                Table VI.C–1 summarizes the benefits
                                          To the extent that the Stage 2 DBPR                  runoff.                                                for the Preferred Regulatory Alternative
                                       changes perceptions of the health risks                                                                        for the Stage 2 DBPR. Benefits estimates
                                                                                               2. Quantified Benefits
                                       associated with drinking water and                                                                             for the other regulatory alternatives
                                       improves taste and odor, it may reduce                    EPA has quantified the benefits                      were derived using the same methods as
                                       actions such as buying bottled water or                 associated with the expected reductions                for the Preferred Regulatory Alternative
                                       installing filtration devices. Any                      in the incidence of bladder cancer. As                 and are presented in the EA.
                                       resulting cost savings would be a                       discussed in Section VI.B, EPA used the                   The confidence bounds of the results
                                       regulatory benefit. Also, as PWSs move                  PAR values from all three approaches to                in Table VI.C–1 reflect uncertainty in
                                       away from conventional treatment to                     estimate the number of bladder cancer                  PAR, uncertainty in the compliance
                                       more advanced technologies, other non-                  cases ultimately avoided annually as a                 forecast and resulting reduction in DBP
                                       health benefits are anticipated besides                 result of the Stage 2 DBPR, shown in                   concentrations, and cessation lag.
                                       better tasting and smelling water. For                  Figure VI.C–1.                                         Confidence bounds of the monetized
                                       example, GAC lowers nutrient                              Table VI.C–1 summarizes the                          benefits also reflect uncertainty in
                                       availability for bacterial growth,                      estimated number of bladder cancer                     valuation parameters. An estimated 26
                                       produces a biologically more stable                     cases avoided as a result of the Stage 2               percent of bladder cancer cases avoided
                                       finished water, and facilitates                         DBPR, accounting for cessation lag and                 are fatal, and 74 percent are non-fatal
                                       management of water quality in the                      the rule implementation schedule, and                  (USEPA 1999b). The monetized benefits
                                       distribution system. Since GAC also                     the monetized value of those cases. The                therefore reflect the estimate of avoiding
                                       removes synthetic organic chemicals                     benefits in Table VI.C–1 were developed                both fatal and non-fatal cancers in those
                                       (SOCs), it provides additional protection               using the PAR value from Villanueva et                 proportions.
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                                                    TABLE VI.C–1.—SUMMARY OF QUANTIFIED BENEFITS FOR THE STAGE 2 DBPR (MILLIONS OF $2003)
                                            Annual average cases avoided                                                          Annualized benefits of cases avoided
                                                                                          Discount rate, WTP for non-                                                            Cessation lag model
                                                                                                  fatal cases
                                           Mean            5th               95th                                                  Mean             5th            95th

                                            279            103               541          3%, Lymphoma ...................           $1,531            $233          $3,536   Smoking/Lung Cancer
                                                                                          7% Lymphoma ....................            1,246             190           2,878
                                                                                          3% Bronchitis ......................          763             165           1,692
                                                                                          7% Bronchitis ......................          621             135           1,376
                                            188             61               399          3%, Lymphoma ...................            1,032             157           2,384   Smoking/Bladder Cancer
                                                                                          7% Lymphoma ....................              845             129           1,950
                                                                                          3% Bronchitis ......................          514             111           1,141
                                                                                          7% Bronchitis ......................          420              91             932
                                            333            138               610          3%, Lymphoma ...................            1,852             282           4,276   Arsenic/Bladder Cancer
                                                                                          7% Lymphoma ....................            1,545             235           3,566
                                                                                          3% Bronchitis ......................          922             200           2,045
                                                                                          7% Bronchitis ......................          769             167           1,704
                                          Notes: Values are discounted and annualized in 2003$. The 90 percent confidence interval for cases incorporates uncertainty in PAR, reduc-
                                       tion in average TTHM and HAA5 concentrations, and cessation lag. The 90 percent confidence bounds for monetized benefits reflect uncertainty
                                       in monetization inputs relative to mean cases. Based on TTHM as an indicator, benefits were calculated using the Villanueva et al. (2003) PAR.
                                       EPA recognizes that benefits may be as low as zero since causality has not yet been established between exposure to chlorinated water and
                                       bladder cancer. Assumes 26 percent of cases are fatal, 74 percent are non-fatal (USEPA 1999b).
                                          Source: Exhibit 6.1, USEPA 2005a.

                                       3. Timing of Benefits Accrual                               exposures. EPA developed cessation lag                  years after the exposure reduction has
                                                                                                   models for DBPs from literature to                      occurred, the annual cases avoided will
                                          EPA recognizes that it is unlikely that                  describe the delayed benefits, in                       be 489 for the smoking/lung cancer
                                       all cancer reduction benefits would be                      keeping with the recommendations of                     cessation lag model, 329 for the
                                       realized immediately upon exposure                          the SAB (USEPA 2001d). Figure VI.C–2                    smoking/bladder cancer cessation lag
                                       reduction. Rather, it is expected that                      illustrates the effects of the cessation lag            model, and 534 cases for the arsenic/
                                       there will likely be some transition                        models. The results from the cessation                  bladder cancer cessation lag model.
                                       period as individual risks reflective of                    lag models show that the majority of the                These represent approximately 84%,
                                       higher past exposures at the time of rule                   potential cases avoided occur within the                57%, and 92%, respectively, of the
                                       implementation become, over time,                           first fifteen years after initial reduced               estimated 581 annual cases ultimately
                                       more reflective of the new lower                            exposure to DBPs. For example, fifteen                  avoidable by the Stage 2 DBPR.

                                         In addition to the delay in reaching a                    six years from rule promulgation to                     treatment by 2016. The delay in
                                       steady-state level of risk reduction as a                   meet the new Stage 2 MCLs, with up to                   exposure reduction resulting from the
                                       result of cessation lag, there is a delay                   a two-year extension possible for capital               rule implementation schedule is
                                       in attaining maximum exposure                               improvements. In general, EPA assumes                   incorporated into the benefits model by
                                       reduction across the entire affected                        that a fairly constant increment of                     adjusting the cases avoided for the given
                                       population that results from the Stage 2                    systems will complete installation of                   year and is illustrated in Table VI.C–2.
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                                       DBPR implementation schedule. For                           new treatment technologies each year,
                                       example, large surface water PWSs have                      with the last systems installing

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                                                                                                                                                           Smoking/lung cancer       Smoking/bladder can-     Arsenic/bladder can-
                                                                                                                                                           cessation lag model         cer cessation lag       cer cessation lag
                                                                                           Year                                                                                             model                    model
                                                                                                                                                             Total       Percent       Total       Percent      Total     Percent

                                       1 ...............................................................................................................           0             0             0          0          0            0
                                       2 ...............................................................................................................           0             0             0          0          0            0
                                       3 ...............................................................................................................           0             0             0          0          0            0
                                       4 ...............................................................................................................           0             0             0          0          0            0
                                       5 ...............................................................................................................           0             0             0          0          0            0
                                       6 ...............................................................................................................          24             4            23          4         45            8
                                       7 ...............................................................................................................          62            11            54          9        110           19
                                       8 ...............................................................................................................         111            19            90         16        187           32
                                       9 ...............................................................................................................         170            29           132         23        275           48
                                       10 .............................................................................................................          220            38           161         28        334           58
                                       11 .............................................................................................................          265            46           184         32        379           65
                                       12 .............................................................................................................          305            53           204         35        412           71
                                       13 .............................................................................................................          341            59           221         38        438           76
                                       14 .............................................................................................................          371            64           237         41        458           79
                                       15 .............................................................................................................          396            68           251         43        475           82
                                       16 .............................................................................................................          416            72           265         46        488           84
                                       17 .............................................................................................................          433            75           278         48        499           86
                                       18 .............................................................................................................          448            77           289         50        509           88
                                       19 .............................................................................................................          460            79           301         52        516           89
                                       20 .............................................................................................................          471            81           311         54        523           90
                                       21 .............................................................................................................          481            83           321         55        528           91
                                       22 .............................................................................................................          489            84           330         57        533           92
                                       23 .............................................................................................................          496            86           339         59        537           93
                                       24 .............................................................................................................          503            87           347         60        541           93
                                       25 .............................................................................................................          509            88           355         61        544           94
                                          Notes: Percent of annual cases ultimately avoidable achieved during each of the first 25 years. The benefits model estimates 581 (90% CB =
                                       229–1,079) annual cases ultimately avoidable using the Villanueva et al. (2003) PAR inputs and including uncertainty in these and DBP reduc-
                                       tions. EPA recognizes that benefits may be as low as zero since causality has not yet been established between exposure to chlorinated water
                                       and bladder cancer.
                                          Source: Summarized from detailed results presented in Exhibits E.38a, E.38e and E.38i, USEPA 2005a.

                                       D. Costs of the Stage 2 DBPR                                                  present value costs, PWS costs, State/                          $77 million per year. The mean and
                                          National costs include those of                                            Primacy agency costs, and non-                                  range of annualized costs are similar at
                                       treatment changes to comply with the                                          quantified costs.                                               a 7 percent discount rate. State costs are
                                       rule as well as non-treatment costs such                                                                                                      estimated to be between $1.70 and $1.71
                                                                                                                     1. Total Annualized Present Value Costs
                                       as for Initial Distribution System                                                                                                            million per year depending on the
                                       Evaluations (IDSEs), additional routine                                         Tables VI.D–1 and VI.D–2 summarize                            discount rate. These estimates are
                                       monitoring, and operational                                                   the average annualized costs for the                            annualized starting with the year of
                                       evaluations. The methodology used to                                          Stage 2 DBPR Preferred Regulatory                               promulgation. Actual dollar costs
                                       estimate costs is described in Section                                        Alternative at 3 and 7 percent discount                         during years when most treatment
                                       VI.B. More detail is provided in the EA                                       rates, respectively. System costs range                         changes are expected to occur would be
                                       (USEPA 2005a). The remainder of this                                          from approximately $55 to $101 million                          somewhat higher (the same is true for
                                       section presents summarized results of                                        annually at a 3 percent discount rate,                          benefits that occur in the future).
                                       EPA’s cost analysis for total annualized                                      with a mean estimate of approximately                           BILLING CODE 6560–50–P
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                                       2. PWS costs                                            installation as well as operation and                  incur some costs. EPA’s analysis
                                                                                               maintenance. Significant PWS costs for                 allocated systems into five categories to
                                          PWS costs for the Stage 2 DBPR                       IDSEs, treatment, and monitoring are                   determine the costs of the IDSE—those
                                       include non-treatment costs of rule                     described in this section, along with a                conducting standard monitoring, SSS,
                                       implementation, Initial Distribution                    sensitivity analysis.                                  VSS, 40/30, and NTNCWS not required
                                       System Evaluations (IDSEs), Stage 2                       a. IDSE costs. Costs and burden                      to do an IDSE. EPA then developed cost
                                       DBPR monitoring plans, additional                       associated with IDSE activities differ                 estimates for each option. Tables VI.D–
                                       routine monitoring, and operational                     depending on whether or not the system                 3, VI.D–4, and VI.D–5 illustrate PWS
                                       evaluations. Systems required to install                performs the IDSE and, if so, which
                                                                                                                                                      costs for IDSE for systems conducting an
                                       treatment to comply with the MCLs will                  option a system chooses. All systems
                                                                                                                                                      SMP, SSS, and 40/30, respectively.
                                       accrue the additional costs of treatment                performing the IDSE are expected to
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                                         b. PWS treatment costs. The number                    forecast. The percent of systems                       VI.D–6. The cost model includes
                                       of plants changing treatment as a result                predicted to make treatment technology                 estimates for the cost of each
                                       of the Stage 2 DBPR and which                           changes and the technologies predicted                 technology; the results of the cost model
                                       technology various systems will install                 to be in place after implementation of                 for PWS treatment costs are summarized
                                       are determined from the compliance                      the Stage 2 DBPR are shown in Table                    in Table VI.D–7.
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                                         c. Monitoring costs. Because systems                  costs for additional routine monitoring                number of samples to be collected from
                                       already sample for the Stage 1 DBPR,                    are determined by the change in the                    the Stage 1 to the Stage 2 DBPR. The

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                                       Stage 2 DBPR monitoring requirements                    number of treatment plants. With this                  increase for some systems but actually
                                       for systems are based only on                           modification in monitoring scheme, the                 decrease from the Stage 1 to the Stage
                                       population served and source water                      average system will have no change in                  2 DBPR for many systems. Table VI.D–
                                       type, while the Stage 1 DBPR                            monitoring costs. The number of                        8 summarizes the estimated additional
                                       requirements are also based on the                      samples required is estimated to                       routine monitoring costs for systems.
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                                       BILLING CODE 6560–50–c

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                                       3. State/Primacy Agency Costs                           is multiplied by the number of labor                   activity based on experience
                                                                                               hours per FTE, the State/Primacy                       implementing previous rules, such as
                                         To estimate State/Primacy Agency                      Agency hourly wage, and the number of                  the Stage 1 DBPR. State/Primacy Agency
                                       costs, the estimated number of full-time                States/Primacy Agencies. EPA estimated                 costs are summarized in Table VI.D–9.
                                       equivalents (FTEs) required per activity                the number of FTEs required per

                                       4. Non-quantified Costs                                 such as changing storage tank operation                E. Household Costs of the Stage 2 DBPR
                                         All significant costs that EPA has                    were also not considered as alternatives                 EPA estimates that, as a whole,
                                       identified have been quantified. In some                to treatment. These might be options for               households subject to the Stage 2 DBPR
                                       instances, EPA did not include a                        systems with a single problem area with                face minimal increases in their annual
                                       potential cost element because its effects              a long residence time. In the absence of               costs. Approximately 86 percent of the
                                       are relatively minor and difficult to                   detailed information needed to evaluate                households potentially subject to the
                                       estimate. For example, it may be less                   situations such as these, EPA has                      rule are served by systems serving at
                                       costly for a small system to merge with                 included a discussion of possible effects              least 10,000 people; these systems
                                       neighboring systems than to add                         where appropriate. In general, however,                experience the lowest increases in costs
                                       advanced treatment. Such changes have                   the expected net effect of such                        due to significant economies of scale.
                                       both costs (legal fees and connecting                   situations is lower costs to PWSs. Thus,               Households served by small systems
                                       infrastructure) and benefits (economies                 the EA tends to present conservatively                 that add treatment will face the greatest
                                       of scale). Likewise, procuring a new                    high estimates of costs in relation to                 increases in annual costs. Table VI.E–1
                                       source of water would have costs for                    non-quantified costs.                                  summarizes annual household cost
                                       new infrastructure, but could result in                                                                        increases for all system sizes.
                                       lower treatment costs. Operational costs
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                                                                                            TABLE VI.E–1.—ANNUAL HOUSEHOLD COST INCREASES.
                                                                                                                                                                                                         Percentage       Percentage
                                                                                                                                                             90th per-              95th per-             of annual        of annual
                                                                                                                     Mean an-         Median an-
                                                                                                 Total number                                               centile an-            centile an-           household        household
                                                                                                                    nual house-       nual house-
                                                                                                 of households                                             nual house-            nual house-              cost in-         cost in-
                                                                                                                    hold cost in-     hold cost in-
                                                                                                     served                                                hold cost in-          hold cost in-           crease <         crease <
                                                                                                                       crease            crease               crease                 crease               $12 (per-       $120 (per-
                                                                                                                                                                                                            cent)            cent)

                                                                                                                 Households Served by All Plants

                                       All Systems ..........................................     101,553,868               $0.62             $0.03                  $0.36                  $0.98                   99           100
                                       All Small Systems ................................          14,261,241                2.20              0.10                   0.79                   2.57                   97           100
                                       SW < 10,000 ........................................         3,251,893                4.58              0.79                   2.69                   7.24                   95            99
                                       SW ≥ 10,000 ........................................        62,137,350                0.46              0.02                   0.35                   1.81                   99           100
                                       GW < 10,000 .......................................         11,009,348                1.49              0.02                   0.39                   0.99                   98           100
                                       GW ≥ 10,000 ........................................        25,155,277                0.13              0.00                   0.03                   0.08                  100           100

                                                                                                       Households Served by Plants Adding Treatment

                                       All Systems ..........................................         10,161,304            $5.53             $0.80                $10.04                 $22.40                    92            99
                                       All Small Systems ................................                591,623            46.48             18.47                168.85                 197.62                    38            89
                                       SW < 10,000 ........................................              285,911            43.05             13.79                173.53                 177.93                    47            85
                                       SW ≥ 10,000 ........................................            9,060,119             2.83              0.80                  6.98                  11.31                    96           100
                                       GW < 10,000 .......................................               305,712            49.69             16.65                109.86                 197.62                    31            92
                                       GW ≥ 10,000 ........................................              509,562             5.97              1.37                 26.82                  33.84                    79           100
                                          Notes: Detail may not add to total due to independent rounding. Number of households served by systems adding treatment will be higher
                                       than households served by plants adding treatment because an entire system will incur costs even if only some of the plants for that system add
                                       treatment (this would result in lower household costs, however).
                                          Source: Exhibit 7.15, USEPA 2005a.

                                       F. Incremental Costs and Benefits of the                          benefit and cost comparisons may be                                are greater due to the additional control
                                       Stage 2 DBPR                                                      unrepresentative of the true net benefits                          of bromate. However, the benefits of
                                          Incremental costs and benefits are                             of the rule because a significant portion                          Alternative 1 are less than the Preferred
                                       those that are incurred or realized in                            of the rule’s potential benefits are not                           Alternative because the Agency is not
                                       reducing DBP exposures from one                                   quantified, particularly potential                                 able to estimate the additional benefits
                                       alternative to the next more stringent                            reproductive and developmental health                              of reducing the bromate MCL.
                                       alternative. Estimates of incremental                             effects (see Section VI.C). Table VI.F–1                           Alternative 1 was determined to be
                                       costs and benefits are useful in                                  shows the incremental monetized costs                              unacceptable due to the potential for
                                       considering the economic efficiency of                            and benefits for each regulatory                                   increased risk of microbial exposure.
                                       different regulatory options considered                           alternative. Evaluation of this table                              Both benefits and costs are greater for
                                       by the Agency. Generally, the goal of an                          shows that incremental costs generally                             Alternative 2 and Alternative 3 as
                                       incremental analysis is to identify the                           fall within the range of incremental                               compared to the Preferred Alternative.
                                       regulatory option where net social                                benefits for each more stringent                                   However, these regulatory alternatives
                                       benefits are maximized. However, the                              alternative. Equally important, the                                do not have the risk-targeted design of
                                       usefulness of this analysis is                                    addition of any benefits attributable to                           the Preferred Alternative. Rather,
                                       constrained when major benefits and/or                            the non-quantified categories would add                            implementation of these stringent
                                       costs are not quantified or not                                   to the benefits without any increase in                            standards would require a large number
                                       monetized. Also, as pointed out by the                            costs.                                                             of systems to change treatment
                                       Environmental Economics Advisory                                     Table VI.F–1 shows that the Preferred                           technology. The high costs of these
                                       Committee of the Science Advisory                                 Alternative is the least-cost alternative.                         regulatory alternatives and the drastic
                                       Board, efficiency is not the only                                 A comparison of Alternative 1 with the                             shift in the nation’s drinking water
                                       appropriate criterion for social decision                         Preferred Alternative shows that                                   practices were considered unwarranted
                                       making (USEPA 2000i).                                             Alternative 1 would have approximately                             at this time. (See Section VI.A of this
                                          For the proposed Stage 2 DBPR,                                 the same benefits as the Preferred                                 preamble for a description of regulatory
                                       presentation of incremental quantitative                          Alternative. The costs of Alternative 1                            alternatives.)

                                                                           TABLE VI.F–1.—INCREMENTAL COSTS AND BENEFITS OF THE STAGE 2 DBPR
                                                                                                          Annual         Annual ben-       Incremental costs                 Incremental benefits               Incremental net bene-
                                         WTP for non-fatal                                                 costs            efits                                                                                       fits
                                                                           Rule alternative
                                       bladder cancer cases                                                                                            C                                   D
                                                                                                             A                B                                                                                          E=D¥C

                                                                                                                       3 Percent Discount Rate
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                                       Lymphoma ...............         Preferred .................              $79          $1,531     $79 ..........................      $1,531 .....................       $1,452
                                                                        Alternative 1 1 ..........               254           1,377     (1) ............................    (1) ............................   (1)
                                                                        Alternative 2 ............               422           5,167     343 ..........................      3,637 .......................      3,294
                                                                        Alternative 3 ............               634           7,130     212 ..........................      1,962 .......................      1,750
                                       Bronchitis .................     Preferred .................               79             763     79 ............................     763 ..........................     684

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                                                               TABLE VI.F–1.—INCREMENTAL COSTS AND BENEFITS OF THE STAGE 2 DBPR—Continued
                                                                                                     Annual         Annual ben-       Incremental costs                 Incremental benefits               Incremental net bene-
                                         WTP for non-fatal                                            costs            efits                                                                                       fits
                                                                         Rule alternative
                                       bladder cancer cases                                                                                       C                                   D
                                                                                                          A              B                                                                                          E=D¥C

                                                                      Alternative 1 1 ..........              254           686     (1) ............................    (1) ............................   (1)
                                                                      Alternative 2 ............              422         2,575     343 ..........................      1,812 .......................      1,469
                                                                      Alternative 3 ............              634         3,552     212 ..........................      978 ..........................     765

                                                                                                                7 Percent Discount Rate

                                       Lymphoma ...............       Preferred .................             $77        $1,246     $77 ..........................      $1,246 .....................       $1,170
                                                                      Alternative 1 1 ..........              242         1,126     (1) ............................    (1) ............................   (1)
                                                                      Alternative 2 ............              406         4,227     330 ..........................      2,981 .......................      2,651
                                                                      Alternative 3 ............              613         5,832     207 ..........................      1,605 .......................      1,399
                                       Bronchitis .................   Preferred .................              77           621     77 ............................     621 ..........................     544
                                                                      Alternative 1 1 ..........              242           561     (1) ............................    (1) ............................   (1)
                                                                      Alternative 2 ............              406         2,105     330 ..........................      1,484 .......................      1,154
                                                                      Alternative 3 ............              613         2,904     207 ..........................      799 ..........................     593
                                          Notes: Estimates are discounted to 2003 and given in 2003 dollars. Based on TTHM as an indicator, Villanueva et al. (2003) for baseline risk,
                                       and smoking/lung cancer cessation lag model. Assumes 26 percent of cases are fatal, 74 percent are non-fatal (USEPA 1999b). EPA recognizes
                                       that benefits may be as low as zero since causality has not yet been established between exposure to chlorinated water and bladder cancer.
                                          1 Alternative 1 appears to have fewer benefits than the Preferred Alternative because it does not incorporate the IDSE, as explained in Chapter
                                       4. Furthermore, this EA does not quantify the benefits of reducing the MCL for bromate (and potentially associated cancer cases), a requirement
                                       that is included only in Alternative 1. This means that Alternative 1 is dominated by the Preferred Alternative in this analysis (having higher costs
                                       than the Preferred Alternative but lower benefits), and so it is not included in the incremental comparison of alternatives (Columns C–E). OMB
                                       states this in terms of comparing cost effectiveness ratios, but the same rule applies to an incremental cost, benefits, or net benefits comparison:
                                       ‘‘When constructing and comparing incremental cost-effectiveness ratios, [analysts] * * * should make sure that inferior alternatives identified by
                                       the principles of strong and weak dominance are eliminated from consideration.’’ (OMB Circular A–4, p. 10)
                                          Source: Exhibit 9.13, USEPA 2005a.

                                       G. Benefits From the Reduction of Co-                        TTHM and HAA5 as indicators for                                      Iodoacetic acid was found to be
                                       occurring Contaminants                                       chlorination DBP occurrence and                                    cytotoxic and genotoxic in Salmonella
                                          Installing certain advanced                               believes that operational and treatment                            and mammalian cells (Plewa et al.
                                       technologies to control DBPs has the                         changes made because of the Stage 2                                2004a) as were some of the
                                       added benefit of controlling other                           DBPR will result in an overall decrease                            halonitromethanes (Kundu et al. 2004;
                                       drinking water contaminants in addition                      in risk.                                                           Plewa et al. 2004b). Although potent in
                                       to those specifically targeted by the                                                                                           these in vitro screening studies, further
                                                                                                    1. Emerging DBPs
                                       Stage 2 DBPR. For example, membrane                                                                                             research is needed to determine if these
                                       technology installed to reduce DBP                              Iodo-DBPs and nitrogenous DBPs                                  DBPs are active in living systems. No
                                       precursors can also reduce or eliminate                      including halonitromethanes are DBPs                               conclusions on human health risk can
                                       many other drinking water                                    that have recently been reported                                   be drawn from such preliminary
                                       contaminants (depending on pore size),                       (Richardson et al. 2002, Richardson                                studies.
                                       including those that EPA may regulate                        2003). One recent occurrence study
                                                                                                    sampled quarterly at twelve surface                                2. N-Nitrosamines
                                       in the future. Removal of any
                                       contaminants that may face regulation                        water plants using different                                          Another group of nitrogenous DBPs
                                       could result in future cost savings to a                     disinfectants across the U.S. for several                          are the N-nitrosamines. A number of N-
                                       water system. Because of the difficulties                    iodo-THMs and halonitromethane                                     nitrosamines exist, and N-
                                       in establishing which systems would be                       species (Weinberg et al. 2002). The                                nitrosodimethylamine (NDMA), a
                                       affected by other current or future rules,                   concentrations of iodo-THMs and                                    probable human carcinogen (USEPA
                                       no estimate was made of the potential                        halonitromethane in the majority of                                1993), has been identified as a potential
                                       cost savings from addressing more than                       samples in this study were less than the                           health risk in drinking water. NDMA is
                                       one contaminant simultaneously.                              analytical minimum reporting levels;                               a contaminant from industrial sources
                                                                                                    plant-average concentrations of iodo-                              and a potential disinfection byproduct
                                       H. Potential Risks From Other                                THM and halonitromethane species                                   from reactions of chlorine or chloramine
                                       Contaminants                                                 were typically less than 0.002 mg/L,                               with nitrogen containing organic matter
                                          Along with the reduction in DBPs                          which is an order of magnitude lower                               and from some polymers used as
                                       from chlorination such as TTHM and                           than the corresponding average                                     coagulant aids. Studies have produced
                                       HAA5 as a resultof the Stage 2 DBPR,                         concentrations of TTHM and HAA5 at                                 new information on the mechanism of
                                       there may be increases in other DBPs as                      those same plants. Chloropicrin, a                                 formation of NDMA, but there is not
                                       systems switch from chlorine to                              halonitromethane species, was also                                 enough information at this time to draw
                                       alternative disinfectants. For all                           measured in the ICR with a median                                  conclusions regarding a potential
                                       disinfectants, many DBPs are not                             concentration of 0.00019 mg/L across all                           increase in NDMA occurrence as
                                       regulated and many others have not yet                       surface water samples. No occurrence                               systems change treatment. Although
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                                       been identified. EPA will continue to                        data exist for the iodoacids due to the                            there are studies that examined the
                                       review new studies on DBPs and their                         lack of a quantitative method and                                  occurrence of NDMA in some water
                                       occurrence levels to determine if they                       standards. Further work on chemical                                systems, there are no systematic
                                       pose possible health risks. EPA                              formation of iodo-DBPs and                                         evaluations of the occurrence of NDMA
                                       continues to support regulation of                           halonitromethanes is needed.                                       and other nitrosamines in U.S. waters.

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                                       Recent studies have provided new                        I. Effects of the Contaminant on the                   J. Uncertainties in the Risk, Benefit, and
                                       occurrence information that shows                       General Population and Groups Within                   Cost Estimates for the Stage 2 DBPR
                                       NDMA forms in both chlorinated and                      the General Population That Are                           For today’s final rule, EPA has
                                       chloraminated systems. Barrett et al.                   Identified As Likely To Be at Greater                  estimated the current baseline risk from
                                       (2003) reported median concentrations                   Risk of Adverse Health Effects                         exposure to DBPs in drinking water and
                                       of less than 2ng/L for the seven chlorine                                                                      projected the risk reduction and cost for
                                       systems studied and less than 3 ng/L for                   EPA’s Office of Water has historically
                                                                                                                                                      various rule alternatives. There is
                                                                                               considered risks to sensitive
                                       13 chloramine systems. Another study                                                                           uncertainty in the risk calculation, the
                                                                                               subpopulations (including fetuses,
                                       demonstrated that factors other than                                                                           benefit estimates, the cost estimates, and
                                                                                               infants, and children) when establishing
                                       disinfectant type may play an important                                                                        the interaction with other regulations.
                                                                                               drinking water assessments, advisories                 The EA has an extensive discussion of
                                       role in the formation of NDMA
                                                                                               and other guidance, and standards                      relevant uncertainties (USEPA 2005a).
                                       (Schreiber and Mitch 2005). More
                                                                                               (USEPA 1989) (56 FR 3526, January 30,                  This section briefly summarizes the
                                       research is underway to determine the
                                                                                               1991) (USEPA 1991). In the case of                     major uncertainties. Table VI.J–1
                                       extent of NDMA occurrence in drinking                   Stage 2 DBPR, maximizing health
                                       water systems. EPA has proposed                                                                                presents a summary of uncertainty in
                                                                                               protection for sensitive subpopulations                the cost and benefit estimates, refers to
                                       monitoring for NDMA under                               requires balancing risks to achieve the
                                       Unregulated Contaminant Monitoring                                                                             the section or appendix of the EA where
                                                                                               recognized benefits of controlling                     the information is introduced, and
                                       Rule 2 (70 FR 49094, at 49103, August                   waterborne pathogens while minimizing
                                       22, 2005) (USEPA 2005m).                                                                                       estimates the potential effects that each
                                                                                               risk of potential DBP toxicity.                        may have on national cost and benefit
                                         Risk assessments have estimated that                  Experience shows that waterborne                       estimates.
                                       the 10¥6 lifetime cancer risk level is 7                disease from pathogens in drinking                        EPA believes that uncertainty in the
                                       ng/L based on induction of tumors at                    water is a major concern for children                  compliance forecast has a potentially
                                       multiple sites. NDMA is also present in                 and other subgroups (e.g., the elderly,                large influence on cost and benefit
                                       food, tobacco smoke, and industrial                     immunocompromised, and pregnant                        estimates for today’s rule. Thus, the
                                       emissions, and additional research is                   women) because of their greater                        Agency has attempted to quantify the
                                       underway to determine the relative                      vulnerabilities (Gerba et al. 1996). EPA               uncertainty by giving equal weight to
                                       exposure of NDMA in drinking water to                   believes DBPs may also potentially pose                two different compliance forecast
                                       these other sources.                                    risks to fetuses and pregnant women                    approaches. One compliance forecast
                                                                                               (USEPA 1998a). In addition, because the                approach is based on the SWAT
                                       3. Other DBPs                                           elderly population (age 65 and above) is               predictions, and the other is based on
                                          Some systems, depending on bromide                   naturally at a higher risk of developing               the ‘‘ICR Matrix Method.’’ The ICR
                                       and organic precursor levels in the                     bladder cancer, their health risks may                 Matrix Method uses the same basic
                                                                                               further increase as a result of long-term              approach as SWAT, but uses TTHM and
                                       source water and technology selection,
                                                                                               DBP exposure (National Cancer Institute                HAA5 data from the ICR directly to
                                       may experience a shift to higher ratios,
                                                                                               2002).                                                 estimate the percent of plants changing
                                       or concentrations, of brominated DBPs                                                                          technology to comply with the Stage 2
                                       while the overall TTHM or HAA5                             In developing this rule, risks to
                                                                                                                                                      DBPR and the resulting DBP reduction.
                                       concentration may decrease. In some                     sensitive subpopulations, including
                                                                                                                                                      To characterize the uncertainty of the
                                       instances where alternative                             children, were taken into account in the
                                                                                                                                                      compliance forecast results, EPA
                                       disinfectants are used, levels of chlorite              assessments of disinfectants and DBPs.
                                                                                                                                                      assumes a uniform distribution between
                                       and bromate may increase as a result of                 More details on sensitive
                                                                                                                                                      SWAT and ICR Matrix Method results
                                       systems switching to chlorine dioxide or                subpopulations can be found in the
                                                                                                                                                      (USEPA 2005a). That is, the cost and
                                       ozone, respectively. However, EPA                       Economic Analysis (USEPA 2005a). For                   benefit estimates presented in the
                                       anticipates that changes in chlorite and                each of the DBPs included in the Stage                 preamble represent the midpoint
                                       bromate concentration as a result of the                2 DBPR, the maximum contaminant                        between costs and benefits estimated
                                       Stage 2 DBPR will be minimal (USEPA                     level goals (MCLG) are derived using the               using the SWAT model, and those
                                       2005a). For most systems, overall levels                most sensitive endpoint among all                      estimated using the ICR Matrix Method.
                                       of DBPs, as well as brominated DBP                      available data and an intraspecies                     Cost estimates using the SWAT model
                                       species, should decrease as a result of                 uncertainty factor of 10 which accounts                are about 25% lower than the midpoint
                                       this rule. EPA continues to believe that                for human variability including                        estimates, while those using the ICR
                                       precursor removal is a highly effective                 sensitive subpopulations, like children.               Matrix Method are about 25% higher.
                                                                                               The Agency has evaluated several                       Benefits estimated using the SWAT
                                       strategy to reduce levels of DBPs.
                                                                                               alternative regulatory options and                     model are about 30% lower than the
                                          EPA also considered the impact this                  selected the one that balances cost with               midpoint estimates, while those using
                                       rule may have on microbial                              significant benefits, including those for              the ICR Matrix Method are about 30%
                                       contamination that may result from                      sensitive subpopulations. The Stage 2                  higher.
                                       altering disinfection practices. To                     DBPR will result in a potential                           EPA believes the compliance forecast
                                       address this concern, the Agency                        reduction in cancer risk and a potential               may be overstated because the
                                       developed this rule jointly with the                    reduction in reproductive and                          technology decision tree does not
                                       Long Term 2 Enhanced Surface Water                      developmental risk to fetuses and                      consider low-cost, non-treatment system
                                       Treatment Rule (LT2ESWTR). EPA                          pregnant women. It should be noted that                improvements that could be used to
                                       expects that the LT2ESWTR provisions                    the LT2ESWTR, which accompanies                        comply with the Stage 2 DBPR. These
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                                       will prevent increases in microbial risk                this rule, reduces pathogens in drinking               improvements, including things like
                                       resulting from the Stage 2 DBPR.                        water and further protects sensitive                   flushing more frequently and managing
                                                                                               subpopulations. See Section VII.G for a                storage facilities to reduce water age,
                                                                                               discussion of EPA’s requirements under                 could be used by systems to reduce
                                                                                               Executive Order 13045.                                 TTHM and HAA5 levels for specific

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                                       locations in their distribution system to                    produce the national average are                                          In a number of different contexts over
                                       meet Stage 2 DBPR MCLs. Thus, the                            uncertain.                                                             the past few years, the Agency has
                                       standard compliance forecast method as                         For the cost estimates, uncertainty                                  considered the relative merits and
                                       developed during the M/DBP FACA                              also exists in baseline data inputs, such                              assumptions encountered when
                                       (with a 20 percent safety margin) is a                       as the total number of disinfecting                                    employing meta-analyses. Cessation lag
                                       reasonable estimation. However, SWAT                         plants and their typical average and                                   modeling is a relatively recent analysis
                                       does not explicitly consider the IDSE.                       design flow rates. Other cost model                                    that the Agency has incorporated into
                                       To address uncertainty in the impact of                      inputs such as labor rates and laboratory                              its risk analyses to more appropriately
                                       the IDSE on the compliance forecast,                         fees also contain uncertainties. In these                              model the timing of health benefits. The
                                       EPA revised the compliance forecast                          cases, EPA has evaluated available data                                specific papers upon which the Stage 2
                                       methodology, assigning equal                                 and estimated a cost input value to
                                                                                                                                                                           analysis is based have been peer
                                       probability to 20 and 25 percent                             represent the average of all water
                                                                                                                                                                           reviewed. However, the Agency believes
                                       operational safety margins. EPA believes                     systems nationally. EPA recognizes that
                                                                                                    there is uncertainty in this average and                               that it is time to consider these Agency-
                                       the 25 percent safety margin is a                                                                                                   wide science issues in a broader sense
                                       reasonable high-end estimate of system                       variability in the characteristics of
                                                                                                    individual systems. The influence of                                   with outside experts to better inform the
                                       response to account for the influences of                                                                                           Agency’s future analyses.
                                       the IDSE. EPA used a spatial variability                     these uncertainties on national cost
                                       analysis to determine the appropriate                        estimates is expected to be fairly minor.                                 For monetization of benefits, EPA
                                       safety margin to use to estimate the                           For the benefits estimates, uncertainty                              uses two alternatives for valuing non-
                                       impact of the IDSE on the compliance                         exists in model inputs such as the                                     fatal bladder cancer. Other
                                       forecast.                                                    estimated PAR values and the cessation                                 uncertainties, such as the linear
                                                                                                    lag models. EPA considered three                                       relationship between DBP reductions
                                          These alternative approaches for the                      approaches to estimate attributable risk:
                                       compliance forecast estimate are used to                                                                                            and reductions in bladder cancer cases
                                                                                                    (1) a range of risk derived from                                       avoided, are discussed qualitatively.
                                       represent a range of possible results and                    individual studies, (2) a risk estimate
                                       are incorporated into the cost and                           from a meta-analysis, and (3) a risk                                      In addition to the uncertainties
                                       benefit models using Monte Carlo                             estimate from a pooled analysis. To                                    quantified as part of the benefits
                                       probability functions. EPA believes this                     quantify uncertainty in cessation lag,                                 evaluation, other uncertainties that have
                                       approach helps inform the reader of the                      three independent cessation lag models                                 not been quantified could result in
                                       likely magnitude of the impact of the                        derived from three different                                           either an over-or under-estimation of the
                                       uncertainties.                                               epidemiological studies are used. Also,                                benefits. Two of the greatest
                                          In addition to quantifying some                           two functional forms are used for each                                 uncertainties affecting the benefits of
                                       uncertainties in the compliance                              of these data sets and uncertainty in the                              the Stage 2 DBPR, benefits from
                                       forecasts, EPA has explicitly accounted                      parameters of those functions is                                       potential reductions of cancers other
                                       for uncertainty in estimated treatment                       included in the analysis. As noted                                     than bladder and benefits from possible
                                       technology costs. Treatment costs are                        previously, causality has not been                                     reductions in potential reproductive and
                                       modeled using a triangular distribution                      established between DBP levels and                                     developmental health effects, are
                                       of ± 30 percent for Capital, and ± 15                        cancer endpoints, so the lower bound of                                unquantified. Both of these factors
                                       percent for O&M costs to recognize that                      potential risk reductions may be as low                                could result in an underestimation of
                                       the assumptions for cost analysis to                         as zero.                                                               quantified Stage 2 DBPR benefits.

                                                                         TABLE VI.J–1.—EFFECTS OF UNCERTAINTIES ON NATIONAL ESTIMATES
                                                                                                           Potential effect on benefit estimate                                   Potential effect on cost estimates
                                                                              Section with
                                       Assumptions for which there           full discussion
                                             is uncertainty                                         Under-esti-                                    Unknown im-             Under-esti-                                   Unknown im-
                                                                             of uncertainty                                Over-estimate                                                          Over-estimate
                                                                                                      mate                                            pact                   mate                                           pact

                                       Uncertainty in the industry           3.4 ................     ..................      ..................   X ...................     ..................     ..................   X
                                         baseline (SDWIS and
                                         1995 CWSS data).
                                       Uncertainty in observed data          3.7 ................     ..................      ..................   X ...................     ..................     ..................   X
                                         and predictive tools used
                                         to characterize DBP oc-
                                         currence for the pre-Stage
                                         1 baseline.
                                       Uncertainty in predictive             Chapter 5,             Quantified in primary analysis (addresses po-                          Quantified in primary analysis (addresses po-
                                         tools used to develop the             Appendix A.             tential underestimate or overestimate)                                 tential underestimate or overestimate)
                                         compliance forecast for
                                         surface water systems
                                         (SWAT and ICR Matrix
                                       Uncertainty in ground water           Chapter 5, A             ..................      ..................   X ...................     ..................     ..................   X
                                         compliance forecast meth-             and B.
                                       Operational safety margin of          5.2 ................     ..................      ..................   X ...................     ..................     ..................   X
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                                       Impacts of the IDSE on the            5.3 ................   Quantified in the primary analysis (addresses                          Quantified in the primary analysis (addresses
                                         compliance forecast for                                               potential underestimate)                                               potential underestimate)
                                         the Preferred Regulatory

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                                                                TABLE VI.J–1.—EFFECTS OF UNCERTAINTIES ON NATIONAL ESTIMATES—Continued
                                                                                                              Potential effect on benefit estimate                                       Potential effect on cost estimates
                                                                              Section with
                                       Assumptions for which there           full discussion
                                             is uncertainty                                          Under-esti-                                        Unknown im-             Under-esti-                                        Unknown im-
                                                                             of uncertainty                                   Over-estimate                                                              Over-estimate
                                                                                                       mate                                                pact                   mate                                                pact

                                       Uncertainty in the PAR                6.1.1 Appen-           Quantified in the primary analysis (addresses
                                         value.                                dix E.                range of potential effects, but true values
                                                                                                     could lie outside range)
                                       Reduction in TTHM and                 6.3.3 .............      .................. .................. X.
                                         HAA5 used as proxies for
                                         all chlorination DBPs.
                                       DBPs have a linear no-                6.2.1 .............         ..................   X.
                                         threshold dose-response
                                         relationship for bladder
                                         cancer effects.
                                       Uncertainty in benefits valu-         6.5.2 .............    Quantified in the primary analysis (addresses
                                         ation inputs.                                                potential underestimate or overestimate)
                                       Benefits of reduced cancers           6.7 ................   Quantified in a sensitivity analysis (addresses
                                         other than bladder cancer                                             potential underestimate)
                                         are not included in the
                                         quantitative analysis.
                                       Value of potential reproduc-          6.8 ................   X.
                                         tive and developmental
                                         health effects avoided is
                                         not quantified in the pri-
                                         mary analysis.
                                       Treatment costs do not in-            7.4.1 .............         ..................        ..................     ..................   X.
                                         clude costs for minor
                                         operational changes pre-
                                         dicted by SWAT.
                                       Median operational and                7.4.1 .............         ..................        ..................     ..................        ..................        ..................   X
                                         water quality parameters
                                         considered for technology
                                         unit costs.
                                       Economies of scale for com-           7.4.1 .............         ..................        ..................     ..................        ..................   X.
                                         bination treatment tech-
                                         nologies not considered.
                                       Possible UV-chloramine                7.4.1 .............         ..................        ..................     ..................        ..................   X.
                                         synergy not taken into ac-
                                       Potential low-cost alter-             7.4.2 .............         ..................        ..................     ..................        ..................   X.
                                         natives to treatment not
                                       Uncertainties in unit costs ...       7.4.3 .............         ..................        ..................     ..................    Quantified in primary analysis (addresses po-
                                                                                                                                                                                   tential overestimate or underestimate)

                                       K. Benefit/Cost Determination for the                         drinking water quality and may allow                                         Table VI.K–1 shows that the Preferred
                                       Stage 2 DBPR                                                  some systems to avoid installing                                          Alternative is the least cost alternative.
                                                                                                     additional technology to meet future                                      The Preferred Alternative has higher
                                          The Agency has determined that the                         drinking water regulations.                                               mean net benefits than Alternative 1.
                                       benefits of the Stage 2 DBPR justify the                         Table VI.K–1 presents net benefits for                                 Alternatives 2 and 3 have higher
                                       costs. As discussed previously, the main                      the four regulatory alternatives                                          benefits than the Preferred Alternative
                                       concern for the Agency and the                                evaluated by EPA. This table shows that                                   but also much greater costs. These
                                       Advisory Committee involved in the                            net benefits are positive for all four                                    regulatory alternatives do not have the
                                       Stage 2 rulemaking process was to                             regulatory alternatives. Generally,
                                       provide more equitable protection from                                                                                                  risk-targeted design of the Preferred
                                                                                                     analysis of net benefits is used to
                                       DBPs across the entire distribution                                                                                                     Alternative. Rather, a large number of
                                                                                                     identify alternatives where benefits
                                       system and reduce high DBP levels. The                        exceed costs, as well as the alternative                                  systems would be required to make
                                       final rule achieves this objective using                      that maximizes net benefits. However,                                     treatment technology changes to meet
                                       the least cost alternative by targeting                       analyses of net benefits should consider                                  the stringent standards under these
                                       sampling locations with high DBP levels                       both quantified and non-quantified                                        regulatory alternatives. Also, because
                                       and modifying how the annual average                          (where possible) benefits and costs. As                                   causality has not been established
                                       DBP level is calculated. This will reduce                     discussed previously with incremental                                     between DBP exposure and bladder
                                       both average DBP levels associated with                       net benefits, the usefulness of this                                      cancer, actual benefits may be as low as
                                       bladder cancer (and possibly other                            analysis in evaluating regulatory                                         zero. EPA is promulgating the preferred
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                                       cancers) and peak DBP levels which are                        alternatives for the Stage 2 DBPR is                                      regulatory alternative because the
                                       potentially associated with reproductive                      somewhat limited because many                                             Agency believes that such a drastic shift
                                       and developmental effects. In addition,                       benefits from this rule are non-                                          in the nation’s drinking water practices
                                       this rule may reduce uncertainty about                        quantified and non-monetized.                                             is not warranted at this time.

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                                       464                      Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                                                             TABLE VI.K–1.—MEAN NET BENEFITS BY REGULATORY ALTERNATIVE ($MILLION)
                                                                                                                                                                                             Mean annual              Mean annual      Mean net
                                                              Rule alternative                                       WTP for non-fatal bladder cancer cases                                     costs                   benefits       benefits

                                                                                                                           3 Percent Discount Rate, 25 Years

                                       Preferred .........................................................       Lymphoma ......................................................                          $78.8           $1,530.8         $1,452
                                       A1 ....................................................................      ....................................................................                  254.1            1,376.6          1,122
                                       A2 ....................................................................      ....................................................................                  421.7            5,167.4          4,746
                                       A3 ....................................................................      ....................................................................                  634.2            7,129.6          6,495
                                       Preferred .........................................................       Bronchitis ........................................................                       78.8              762.8            684
                                       A1 ....................................................................      ....................................................................                  254.1              685.9            432
                                       A2 ....................................................................      ....................................................................                  421.7            2,574.6          2,153
                                       A3 ....................................................................      ....................................................................                  634.2            3,552.2          2,918

                                                                                                                           7 Percent Discount Rate, 25 Years

                                       Preferred .........................................................       Lymphoma ......................................................                          $76.8           $1,246.5         $1,170
                                       A1 ....................................................................      ....................................................................                  241.8            1,126.4            885
                                       A2 ....................................................................      ....................................................................                  406.4            4,227.2          3,821
                                       A3 ....................................................................      ....................................................................                  613.1            5,832.4          5,219
                                       Preferred .........................................................       Bronchitis ........................................................                       76.8              620.7            544
                                       A1 ....................................................................      ....................................................................                  241.8              560.8            319
                                       A2 ....................................................................      ....................................................................                  406.4            2,104.6          1,698
                                       A3 ....................................................................      ....................................................................                  613.1            2,903.8          2,291
                                         Notes: Estimates are discounted to 2003 and given in 2003 dollars. Based on TTHM as an indicator, Villanueva et al. (2003) for baseline risk,
                                       and smoking/lung cancer cessation lag model. Assumes 26 percent of cases are fatal, 74 percent are non-fatal (USEPA 1999b). EPA recognizes
                                       that benefits may be as low as zero since causality has not yet been established exposure to chlorinated water and bladder cancer.
                                         Source: Exhibits 9.10 and 9.11, USEPA 2005a.

                                          The Agency also compared the costs                                       the benefits and costs of the rule, but                                      for the preferred alternative seems
                                       and benefits for each regulatory                                            should not be used to compare                                                favorable when compared to the
                                       alternative by calculating which option                                     alternatives because an alternative with                                     willingness to pay estimates. Additional
                                       is the most cost-effective. The cost-                                       the lowest cost per illness/death                                            information about this analysis and
                                       effectiveness analysis compares the cost                                    avoided may not result in the highest                                        other methods of comparing benefits
                                       of the rule per bladder cancer case                                         net benefits. Table VI.K–2 shows the                                         and costs can be found in the EA
                                       avoided. This cost-effectiveness                                            cost of the rule per case avoided. This                                      (USEPA 2005a).
                                       measure is another way of examining                                         table shows that cost per case avoided

                                                  TTHM AS DBP INDICATOR AND SMOKING/LUNG CANCER CESSATION LAG MODEL ($MILLIONS, 2003)
                                                                                                                                                                                                                        Cost per case avoided
                                                                                                                 Rule alternative
                                                                                                                                                                                                                          3%             7%

                                       Preferred ..................................................................................................................................................................            $.033          $.041
                                       Alternative 1 .............................................................................................................................................................             1.18           1.42
                                       Alternative 2 .............................................................................................................................................................             0.52           0.63
                                       Alternative 3 .............................................................................................................................................................             0.57           0.69
                                          1 The cost effectiveness ratios are a potentially a high estimate because regulatory costs in the numerator are not adjusted by subtracting the
                                       avoided medical costs associated with cases avoided to produce a net cost numerator. Subtraction of theses costs would not be expected to
                                       alter the ranking of alternatives. In the case where thresholds of maximum public expenditure per case avoided are prescribed, defining the nu-
                                       merator more precisely by making such adjustments would be appropriate.
                                          Notes: In reference to conducting incremental CEA, OMB states that analyst should make sure that ‘‘When constructing and comparing incre-
                                       mental cost-effectiveness ratios, [analysts] should make sure that inferior alternatives identified by the principles of strong and weak dominance
                                       are eliminated from consideration’’ (OMB Circular A–4, p. 10). Alternative 1 is dominated by the Preferred Alternative and is therefore not in-
                                       cluded in the incremental analysis. The reason for this domination is mainly that the Preferred Alternative includes IDSE and Alternative 1 does
                                       not; and to a lesser degree because the bromate control included in Alternative 1 increases the costs but the benefits of this control are not
                                       quantified at this time. Alternative 2 is compared directly to the Preferred Alternative (skipping Alternative 1) in this analysis. Cost per case avoid-
                                       ed is in year 2003 dollars ($Millions), discounted for the 25 year analysis period to year 2005.
                                          Source: Exhibit 9.14, USEPA, 2005a.

                                       L. Summary of Major Comments                                                example, unanticipated risk issues, and                                      1. Interpretation of Health Effects
                                                                                                                   valuation of cancer cases avoided. The                                       Studies
                                         EPA received significant public                                           following discussion summarizes public
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                                       comment on the analysis of benefits and                                     comment in these areas and EPA’s                                               EPA requested comment on the
                                       costs of the proposed Stage 2 DBPR in                                       responses.                                                                   conclusions of the cancer health effects
                                       the following areas: interpretation of                                                                                                                   section and the epidemiology and
                                       health effects studies, derivation of                                                                                                                    toxicology studies discussed. A number
                                       benefits, use of SWAT, illustrative                                                                                                                      of comments questioned the overall

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                                       interpretation of the studies presented                 science support the incremental nature                 confounders. One commenter supported
                                       by EPA. A few comments pointed out                      of change in today’s rule.                             EPA review of the Villanueva (2003)
                                       missed studies. Commenters also asked                      EPA did not include all findings from               meta-analysis, stating that this was the
                                       about concordance between cancer                        every study in the proposed DBPR                       best available data on the issue.
                                       epidemiology and toxicology. Some                       preamble because the intent was to                        EPA revised the methodology for
                                       commenters also felt EPA did not                        provide a summary overview and more                    calculating PAR values for bladder
                                       discuss the broad range of risks from                   importantly, the Agency’s conclusions                  cancer associated with exposure to
                                       DBPs other than the ones regulated.                     regarding the weight of evidence. The                  chlorinated drinking water by
                                          The Agency continues to believe that,                epidemiology literature has                            considering three different analytical
                                       although there is not a causal link, the                inconsistencies in its findings on the                 approaches as described in Section
                                       cancer literature points to an association              relationship between various                           V.B.2. EPA used the PAR values from all
                                       between bladder cancer and potentially                  reproductive and developmental health                  three approaches to estimate the number
                                       rectal and colon cancer and exposure to                 effects and DBPs. In this final preamble,              of bladder cancer cases ultimately
                                       chlorinated surface water. EPA has                      EPA describes how recent studies since                 avoided annually as a result of the Stage
                                       included in today’s preamble the                        the proposal further inform the                        2 DBPR. Taken together, the three
                                       literature that commenters pointed out                  perspective of overall risk from                       approaches provide a reasonable
                                       as missing and expands on its                           exposure to DBPs. EPA continues to                     estimate of the range of potential risk.
                                       discussion of non-regulated DBPs.                       believe that studies indicate a potential              For simplicity, EPA used the Villanueva
                                          EPA believes that a lack of bladder                  hazard.                                                et al. (2003) study to calculate the
                                       cancer effect in toxicological studies                                                                         annual benefits of the rule. The benefit
                                                                                               2. Derivation of Benefits
                                       does not negate the findings in                                                                                estimates derived from Villanueva et al.
                                                                                                  EPA received numerous comments on                   (2003) capture a substantial portion of
                                       epidemiological studies at this time.                   the derivation of benefits from
                                       Tumor site concordance between                                                                                 the overall range of results, reflecting
                                                                                               occurrence estimates for the Stage 2                   the uncertainty in both the underlying
                                       human and test animal is not necessary                  DBPR. The majority of the comments
                                       to determine carcinogenic potential.                                                                           OR and PAR values, as well as the
                                                                                               provided addressed EPA’s use of a                      uncertainty in DBP reductions for Stage
                                       While there is evidence from human                      cessation lag model to estimate the
                                       cancer epidemiology studies that                                                                               2. More details on the PAR analysis can
                                                                                               timing of benefits and a PAR analysis to               be found in the EA (USEPA 2005a).
                                       lifetime consumption of the DBP                         estimate reduced risks. Several
                                       mixture within chlorinated surface                      commenters opposed the cessation lag                   3. Use of SWAT
                                       water poses a bladder cancer risk, the                  model proposed by EPA, suggesting that                    Comments received on the use of
                                       specific causative constituents have not                EPA use a longer cessation lag period or               SWAT for the compliance forecast
                                       been identified. EPA will continue to                   conduct a sensitivity analysis on the                  claimed that the model probably
                                       evaluate new mode-of-action data as it                  cessation lag exponent.                                underestimates DBP occurrence levels
                                       becomes available.                                         In the effort to develop a cessation lag            and hence underestimates compliance
                                          Several comments were received on                    model specific to DBPs, EPA reviewed                   costs. Other commenters supported
                                       EPA’s characterization of the literature                the available epidemiological literature               EPA’s occurrence estimation methods
                                       on reproductive and developmental                       for information relating to the timing of              and results. Some commenters added
                                       health risk. Some commenters wanted                     exposure and response, but could not                   that monitoring under the IDSE will
                                       EPA to characterize reproductive and                    identify any studies that could, alone or              produce different results than
                                       developmental health effects more                       in combination, support a specific                     monitoring for the ICR and that SWAT
                                       strongly, stating that current research                 cessation lag model for DBPs in                        did not capture these changes.
                                       shows more evidence for these effects                   drinking water. Thus, in keeping with                     EPA describes in detail the limitations
                                       than described in the proposed                          the SAB recommendation to consider                     of SWAT as well as all assumptions and
                                       preamble. Others thought that EPA’s                     other models in the absence of specific                uncertainties associated with the model
                                       characterization in the proposal was too                cessation lag information (USEPA                       in the EA published with today’s rule.
                                       strong, and that EPA had                                2001d), EPA explored the use of                        EPA believes that, for the reasons stated
                                       overemphasized these health concerns.                   information on other carcinogens that                  below, the standard compliance forecast
                                       Some commenters noted that certain                      could be used to characterize the                      method using SWAT, as developed
                                       published studies were missing from                     influence of cessation lag in calculating              during the M-DBP FACA, provides a
                                       EPA’s risk discussion.                                  benefits. The benefit analysis for today’s             reasonable prediction of national
                                          EPA believes that the characterization               rule uses three cessation lag models,                  treatment changes and resulting DBP
                                       of reproductive and developmental risks                 which allows for a better                              levels anticipated for the Stage 2 DBPR:
                                       in the final Stage 2 DBPR preamble is                   characterization of uncertainty than did                  1. SWAT predictive equations for
                                       appropriate based on the weight of                      the approach used in the proposal. More                TTHM and HAA5 were calibrated to
                                       evidence evaluation of the reproductive                 details on this analysis are in the EA                 ICR-observed TTHM and HAA5 data.
                                       and developmental epidemiology                          (USEPA 2005a).                                            2. SWAT estimates are based on 12
                                       database described in Section III.C. EPA                   Additional comments were received                   months of influent water quality data,
                                       considered comments and incorporated                    on the use of PAR values derived from                  treatment train information, and related
                                       additional and recent studies into its                  epidemiology studies to determine the                  characteristics for the 273 ICR surface
                                       characterization of health risks in                     number of bladder cancer cases                         water plants. EPA believes the ICR data
                                       today’s final preamble. While no causal                 attributable to DBP exposure. Some                     provide a robust basis for the
                                       link has been established, EPA’s                        commenters remarked that there was                     compliance forecast as it represents
                                       evaluation of the available studies                     not sufficient evidence in the                         significant variability with respect to
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                                       continues to indicate a potential health                epidemiology studies used to develop a                 factors influencing DBP formation,
                                       hazard that warrants additional                         reliable PAR estimate. A key issue                     including temperature, residence time,
                                       regulatory action beyond the Stage 1                    expressed in the comments was that                     and geographical region.
                                       DBPR. The inconsistencies and                           studies that developed the PAR                            3. EPA uses a ‘‘delta’’ approach to
                                       uncertainties remaining in the available                estimates did not adequately control for               reduce the impact of uncertainty in

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                                       SWAT’s predictive equations for TTHM                    experience significant year-to-year                    further consider these risks when
                                       and HAA5. Under this approach, EPA 1)                   variability in TTHM and HAA5                           developing the final Stage 2 DBPR.
                                       estimates the difference in technology                  occurrence.                                               EPA has addressed the occurrence of
                                       and TTHM and HAA5 concentration                           As some commenters noted, any                        other DBPs in Section VI.H of this
                                       predictions between pre-Stage 1 and                     underestimation in costs as a result of                document and in the EA (USEPA
                                       post-Stage 1; 2) estimates the difference               the compliance forecast is associated                  2005a). Levels of some DBPs may
                                       in technology and TTHM and HAA5                         with an underestimation in the benefits.               increase because of treatment changes
                                       concentration predictions between pre-                  Accordingly, EPA adjusted both cost                    anticipated as a result of today’s rule.
                                       Stage 1 and post-Stage 2; and 3)                        and benefits estimates based on the ICR                However, these DBPs generally occur at
                                       subtracts the result of the first estimate              Matrix Method and the impact of the                    much lower levels than TTHM and
                                       from the second estimate to predict the                 IDSE for the upper end of the                          HAA5, often more than an order of
                                       impacts between Stage 1 and Stage 2.                    compliance forecast range.                             magnitude less (USEPA 2005f, Weinberg
                                       Since each predictive estimate has bias                                                                        et al. 2002). For NDMA, studies have
                                                                                               4. Illustrative Example
                                       in the same direction, EPA believes that                                                                       shown formation in both chlorinated
                                       this methodology minimized overall                         Many comments were received on the                  and chloraminated systems (Barrett et
                                       predictive error.                                       illustrative calculation of fetal loss                 al. 2003). The uncertainties surrounding
                                          In response to commenters concerns                   benefits included in the proposed EA.                  NDMA formation make determinations
                                       about potential uncertainties in the                    Many commenters recommended that                       regarding the impact of the Stage 2
                                       SWAT predictions, EPA also developed                    EPA remove this calculation because of                 DBPR difficult. In addition, other routes
                                       the ‘‘ICR Matrix Method.’’ The ICR                      uncertainties in the underlying data.                  of exposure appear to be more
                                       Matrix Method uses TTHM and HAA5                        Other commenters, however, expressed                   significant than drinking water. Dietary
                                       data from the ICR to estimate the                       support for this calculation because of                sources of NDMA include preserved
                                       percent of plants changing technology to                the magnitude of potential benefits, and               meat and fish products, beer and
                                       comply with the Stage 2 DBPR and the                    suggested that EPA include these                       tobacco. EPA is looking at calculating
                                       resulting DBP reduction. The EA                         benefits in its primary analysis.                      the relative source contribution of these
                                       includes a detailed description of the                     EPA believes that the reproductive                  routes of exposure compared to drinking
                                       ICR Matrix Method (USEPA 2005a). In                     and developmental epidemiologic data,                  water.
                                       the analysis for today’s rule, EPA gives                although not conclusive, are suggestive                   EPA continues to support the use of
                                       equal weight to SWAT and ICR Matrix                     of potential health effects in humans                  TTHM and HAA5 as indicators for DBP
                                       Method predictions in estimating Stage                  exposed to DBPs. EPA does not believe                  regulation. The presence of TTHM and
                                       2 compliance forecasts and resultant                    the available evidence provides an                     HAA5 is representative of the
                                       reductions in DBP exposure. The ICR                     adequate basis for quantifying potential               occurrence of many other chlorination
                                       Matrix Method is also used to estimate                  reproductive and developmental risks.                  DBPs; thus, a reduction in the TTHM
                                       reductions in the occurrence of peak                    Nevertheless, given the widespread                     and HAA5 generally indicates an overall
                                       TTHM and HAA5 concentrations                            nature of exposure to DBPs, the                        reduction of DBPs. EPA also supports
                                       because SWAT-predicted TTHM and                         importance our society places on                       additional research on unregulated and
                                       HAA5 concentrations are valid only                      reproductive and developmental health,                 unknown DBPs to ensure continual
                                       when considering national averages, not                 and the large number of fetal losses                   public health protection.
                                       at the plant level.                                     experienced each year in the U.S.
                                                                                               (nearly 1 million), the Agency believes                6. Valuation of Cancer Cases Avoided
                                          EPA revised the Stage 2 DBPR
                                       compliance forecast methodology to                      that it is appropriate to provide some                    A number of commenters remarked
                                       quantify the potential impacts of the                   quantitative indication of the potential               on the valuation of cancer cases
                                       IDSE for large and medium surface                       risk suggested by some of the published                avoided. Some commenters supported
                                       water systems. For these systems, EPA                   results on reproductive and                            the use of value of statistical life (VSL)
                                       predicted compliance implications                       developmental endpoints, despite the                   analysis in monetizing the benefits of
                                       using a safety margin of both 20 and 25                 absence of certainty regarding a causal                fatal bladder cancer cases avoided.
                                       percent based on an analysis of spatial                 link between disinfection byproducts                   Comments were also received in
                                       variability in TTHM and HAA5                            and these risks and the inconsistencies                support of the addition of expected
                                       occurrence. EPA assigned equal                          between studies. However, the Agency                   medical costs for treating fatal bladder
                                       probability to the 20 and 25 percent                    is unable at this time to either develop               cancer cases to the VSL estimates. Other
                                       safety margins because both alternatives                a specific estimate of the value of                    commenters recommended that EPA
                                       are considered equally plausible. These                 avoiding fetal loss or to use a benefit                further review the use of willingness-to-
                                       changes result in a wider uncertainty                   transfer methodology to estimate the                   pay estimates used to value the non-
                                       range for the compliance cost estimates                 value from studies that address other                  fatal cancer cases avoided. These
                                       than under the EA of the proposed rule.                 endpoints.                                             comments stated concern over the
                                       EPA assumes the 20 percent operational                                                                         similarity of bronchitis and lymphoma
                                       safety margin accounts for variability in               5. Unanticipated Risk Issues                           to bladder cancer and the resulting
                                       small surface water systems and all                        Comments were received that                         limitation of benefits transfer.
                                       ground water systems. Small systems                     expressed concern about unanticipated                     EPA thanks commenters for
                                       are not expected to find significantly                  risks that could result from the                       expressing support of the use of VSL
                                       higher levels that affect their                         proposed Stage 2 DBPR. Several                         and valuation of fatal bladder cancer
                                       compliance as a result of the IDSE                      commenters remarked that regulation of                 cases. EPA acknowledges that the
                                       because their distribution systems are                  TTHM and HAA5 would not control                        willingness to pay (WTP) to avoid
                                       not as complex as large systems.                        levels of other DBPs that may be more                  curable lymphoma or chronic bronchitis
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                                       Additionally, the IDSE is not expected                  toxic than these indicator compounds,                  is not a perfect substitute for the WTP
                                       to significantly impact the compliance                  such as NDMA. Some commenters                          to avoid a case of non-fatal bladder
                                       forecast for ground water systems                       supported future research on the                       cancer. However, non-fatal internal
                                       because they have more consistent                       potential health effects of other DBPs.                cancers, regardless of type, generally
                                       source water quality and do not                         Other comments suggested that EPA                      present patients with very similar

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                                       treatment, health, and long-term quality                to evaluate compliance with the rule.                  requirements contained in this final
                                       of life implications, including surgery,                For the first three years after Stage 2                rule.
                                       radiation or chemotherapy treatments                    DBPR promulgation, the major
                                                                                                                                                      C. Regulatory Flexibility Act
                                       (with attendant side effects), and                      information requirements involve
                                       generally diminished vitality over the                  monitoring activities, which include                      The Regulatory Flexibility Act (RFA)
                                       duration of the illness. In the absence of              conducting the IDSE and submission of                  generally requires an agency to prepare
                                       more specific WTP studies, EPA                          the IDSE report, and tracking                          a regulatory flexibility analysis for any
                                       believes the WTP values for avoiding a                  compliance. The information collection                 rule subject to notice and comment
                                       case of curable lymphoma or a case of                   requirements are mandatory (Part 141),                 rulemaking requirements under the
                                       chronic bronchitis provides a                           and the information collected is not                   Administrative Procedure Act or other
                                       reasonable, though not definitive,                      confidential.                                          statute unless the agency certifies that
                                       substitute for the value of avoiding non-                  The estimate of annual average                      the rule will not have a significant
                                       fatal bladder cancer.                                   burden hours for the Stage 2 DBPR for                  economic impact on a substantial
                                                                                               systems and States is 228,529 hours.                   number of small entities. Small entities
                                       VII. Statutory and Executive Order                                                                             include small businesses, small
                                       Reviews                                                 This estimate covers the first three years
                                                                                               of the Stage 2 DBPR and most of the                    organizations, and small governmental
                                       A. Executive Order 12866: Regulatory                    IDSE (small system reports are not due                 jurisdictions.
                                       Planning and Review                                                                                               The RFA provides default definitions
                                                                                               until the fourth year). The annual
                                                                                                                                                      for each type of small entity. Small
                                         Under Executive Order 12866, [58 FR                   average aggregate cost estimate is $9.8
                                                                                                                                                      entities are defined as: (1) A small
                                       51735, (October 4, 1993)] the Agency                    million for operation and maintenance
                                                                                                                                                      business as defined by the Small
                                       must determine whether the regulatory                   as a purchase of service for lab work and
                                                                                                                                                      Business Administrations’s (SBA)
                                       action is ‘‘significant’’ and therefore                 $6.6 million is associated with labor.
                                                                                                                                                      regulations at 13 CFR 121.201; (2) a
                                       subject to OMB review and the                           The annual burden hour per response is
                                                                                                                                                      small governmental jurisdiction that is a
                                       requirements of the Executive Order.                    4.18 hours. The frequency of response                  government of a city, county, town,
                                       The Order defines ‘‘significant                         (average responses per respondent) is                  school district or special district with a
                                       regulatory action’’ as one that is likely               7.59 annually. The estimated number of                 population of less than 50,000; and (3)
                                       to result in a rule that may:                           likely respondents is 7,202 per year (the              a small organization that is any ‘‘not-for-
                                         (1) Have an annual effect on the                      product of burden hours per response,                  profit enterprise which is independently
                                       economy of $100 million or more or                      frequency, and respondents does not                    owned and operated and is not
                                       adversely affect in a material way the                  total the annual average burden hours                  dominant in its field.’’ However, the
                                       economy, a sector of the economy,                       due to rounding). Because disinfecting                 RFA also authorizes an agency to use
                                       productivity, competition, jobs, the                    systems have already purchased basic                   alternative definitions for each category
                                       environment, public health or safety, or                monitoring equipment to comply with                    of small entity, ‘‘which are appropriate
                                       State, local, or Tribal governments or                  the Stage 1 DBPR, EPA assumes no                       to the activities of the agency’’ after
                                       communities;                                            capital start-up costs are associated with             proposing the alternative definition(s) in
                                         (2) Create a serious inconsistency or                 the Stage 2 DBPR ICR.                                  the Federal Register and taking
                                       otherwise interfere with an action taken                   Burden means the total time, effort, or             comment. 5 U.S.C. 601(3)–(5). In
                                       or planned by another agency;                           financial resources expended by persons                addition, to establish an alternative
                                         (3) Materially alter the budgetary                    to generate, maintain, retain, or disclose             small business definition, agencies must
                                       impact of entitlements, grants, user fees,              or provide information to or for a                     consult with SBA’s Chief Council for
                                       or loan programs or the rights and                      Federal agency. This includes the time                 Advocacy.
                                       obligations of recipients thereof; or                   needed to review instructions; develop,                   For purposes of assessing the impacts
                                         (4) Raise novel legal or policy issues                acquire, install, and utilize technology               of today’s rule on small entities, EPA
                                       arising out of legal mandates, the                      and systems for the purposes of                        considered small entities to be public
                                       President’s priorities, or the principles               collecting, validating, and verifying                  water systems serving 10,000 or fewer
                                       set forth in the Executive Order.                       information, processing and                            persons. As required by the RFA, EPA
                                         Pursuant to the terms of Executive                    maintaining information, and disclosing                proposed using this alternative
                                       Order 12866, it has been determined                     and providing information; adjust the                  definition in the Federal Register (63 FR
                                       that this rule is a ‘‘significant regulatory            existing ways to comply with any                       7620, February 13, 1998), requested
                                       action.’’ As such, this action was                      previously applicable instructions and                 public comment, consulted with the
                                       submitted to OMB for review. Changes                    requirements; train personnel to be able               Small Business Administration (SBA),
                                       made in response to OMB suggestions or                  to respond to a collection of                          and finalized the alternative definition
                                       recommendations will be documented                      information; search data sources;                      in the Consumer Confidence Reports
                                       in the public record.                                   complete and review the collection of                  regulation (63 FR 44511, August 19,
                                                                                               information; and transmit or otherwise                 1998). As stated in that Final Rule, the
                                       B. Paperwork Reduction Act                              disclose the information.                              alternative definition is applied to this
                                         The Office of Management and Budget                      An agency may not conduct or                        regulation as well.
                                       (OMB) has approved the information                      sponsor, and a person is not required to                  After considering the economic
                                       collection requirements contained in                    respond to a collection of information                 impacts of today’s final rule on small
                                       this rule under the provisions of the                   unless it displays a currently valid OMB               entities, I certify that this action will not
                                       Paperwork Reduction Act, 44 U.S.C.                      control number. The OMB control                        have a significant economic impact on
                                       3501 et seq. and has assigned OMB                       numbers for EPA’s regulations in 40                    a substantial number of small entities.
                                       control number 2040–0265 (USEPA                         CFR are listed in 40 CFR part 9. In                    The small entities regulated by this final
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                                       2005n).                                                 addition, EPA is amending the table in                 rule are PWSs serving fewer than 10,000
                                         The information collected as a result                 40 CFR part 9 of currently approved                    people. We have determined that 92
                                       of this rule will allow the States and                  OMB control numbers for various                        small surface water and ground water
                                       EPA to determine appropriate                            regulations to list the regulatory                     under the direct influence of surface
                                       requirements for specific systems, and                  citations for the information                          water (GWUDI) systems (or 2.16% of all

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                                       small surface water and GWUDI systems                   States must provide a minimum of 15%                   promulgating an EPA rule for which a
                                       affected by the Stage 2 DBPR) will                      of the available funds for loans to small              written statement is needed, section 205
                                       experience an impact of 1% or greater                   communities. A State has the option of                 of the UMRA generally requires EPA to
                                       of average annual revenues. Of the 92,                  providing up to 30% of the grant                       identify and consider a reasonable
                                       40 small surface water and GWUDI                        awarded to the State to furnish                        number of regulatory alternatives and
                                       systems (or 0.94% of all small surface                  additional assistance to State-defined                 adopt the least costly, most cost-
                                       water and GWUDI systems affected by                     disadvantaged communities. This                        effective or least burdensome alternative
                                       the Stage 2 DBPR) will experience an                    assistance can take the form of lower                  that achieves the objectives of the rule.
                                       impact of 3% or greater of average                      interest rates, principal forgiveness, or              The provisions of section 205 do not
                                       annual revenues. Further, 354 small                     negative interest rate loans. The State                apply when they are inconsistent with
                                       ground water systems (or 1.02% of all                   may also extend repayment terms of                     applicable law. Moreover, section 205
                                       small ground water systems affected by                  loans for disadvantaged communities to                 allows EPA to adopt an alternative other
                                       the Stage 2 DBPR) will experience an                    up to 30 years. A State can set aside up               than the least costly, most cost-effective
                                       impact of 1% or greater of average                      to 2% of the grant to provide technical                or least burdensome alternative if the
                                       annual revenues. Of the 354, 45 small                   assistance to PWSs serving communities                 Administrator publishes with the final
                                       ground water systems (or 0.13% of all                   with populations fewer than 10,000.                    rule an explanation why that alternative
                                       small ground water systems affected by                    In addition to the DWSRF, money is                   was not adopted. Before EPA establishes
                                       the Stage 2 DBPR) will experience an                    available from the Department of                       any regulatory requirements that may
                                       impact of 3% or greater of average                      Agriculture’s Rural Utility Service                    significantly or uniquely affect small
                                       annual revenues.                                        (RUS) and Housing and Urban                            governments, including Tribal
                                          Although this final rule will not have               Development’s Community                                governments, it must have developed
                                       a significant economic impact on a                      Development Block Grant (CDBG)                         under section 203 of the UMRA a small
                                       substantial number of small entities,                   program. RUS provides loans,                           government agency plan. The plan must
                                       EPA nonetheless has tried to reduce the                 guaranteed loans, and grants to improve,               provide for notifying potentially
                                       impact of this rule on small entities. The              repair, or construct water supply and                  affected small governments, enabling
                                       Stage 2 DBPR contains a number of                       distribution systems in rural areas and                officials of affected small governments
                                       provisions to minimize the impact of                    towns of up to 10,000 people. In fiscal                to have meaningful and timely input in
                                       the rule on systems generally, and on                   year 2003, RUS had over $1.5 billion of                the development of EPA regulatory
                                       small systems in particular. For                        available funds for water and                          proposals with significant Federal
                                       example, small systems have a longer                    environmental programs. The CDBG                       intergovernmental mandates, and
                                       time frame to comply with requirements                  program includes direct grants to States,              informing, educating, and advising
                                       than large systems (see § 141.600(c) and                which in turn are awarded to smaller                   small governments on compliance with
                                       § 141.620(c)). The final rule determines                                                      ˜
                                                                                               communities, rural areas, and colonas in               the regulatory requirements.
                                       monitoring frequency based on                           Arizona, California, New Mexico, and
                                                                                                                                                         EPA has determined that this rule
                                       population rather than plant-based                      Texas and direct grants to U.S.
                                                                                                                                                      may contain a Federal mandate that
                                       monitoring requirements (see § 141.605                  territories and trusts. The CDBG budget
                                                                                                                                                      results in expenditures of $100 million
                                       and § 141.621(a)) as proposed. Small                    for fiscal year 2003 totaled over $4.4
                                                                                                                                                      or more for the State, Local, and Tribal
                                       systems will also have to take fewer                    billion.
                                                                                                 Although not required by the RFA to                  governments, in the aggregate in the
                                       samples than large systems due to the
                                       40/30 waiver (see § 141.603(a)), for                    convene a Small Business Advocacy                      private sector in any one year. While the
                                       which small, ground water systems are                   Review (SBAR) Panel because EPA                        annualized costs fall below the $100
                                       expected to be able to qualify, and the                 determined that the proposed rule                      million threshold, the costs in some
                                       very small system waiver (see                           would not have a significant economic                  future years may be above the $100
                                       § 141.604).                                             impact on a substantial number of small                million mark as public drinking water
                                          Funding may be available from                        entities, EPA did convene a panel to                   systems make capital investments and
                                       programs administered by EPA and                        obtain advice and recommendations                      finance these through bonds, loans, and
                                       other Federal agencies to assist small                  from representatives of the small                      other means. EPA’s year by year cost
                                       PWSs in complying with the Stage 2                      entities potentially subject to this rule’s            tables do not reflect that investments
                                       DBPR. The Drinking Water State                          requirements. For a description of the                 through bonds, loans, and other means
                                       Revolving Fund (DWSRF) assists PWSs                     SBAR Panel and stakeholder                             spread out these costs over many years.
                                       with financing the costs of                             recommendations, please see the                        The cost analysis in general does not
                                       infrastructure needed to achieve or                     proposed rule (USEPA 2003a).                           consider that some systems may be
                                       maintain compliance with SDWA                                                                                  eligible for financial assistance such as
                                                                                               D. Unfunded Mandates Reform Act                        low-interest loans and grants through
                                       requirements. Through the DWSRF,
                                       EPA awards capitalization grants to                       Title II of the Unfunded Mandates                    such programs as the Drinking Water
                                       States, which in turn can provide low-                  Reform Act of 1995 (UMRA), Public                      State Revolving Fund.
                                       cost loans and other types of assistance                Law 104–4, establishes requirements for                   As noted earlier, today’s final rule is
                                       to eligible PWSs. Loans made under the                  Federal agencies to assess the effects of              promulgated pursuant to section 1412
                                       program can have interest rates between                 their regulatory actions on State, local,              (b)(1)(A) of the Safe Drinking Water Act
                                       0 percent and market rate and                           and Tribal governments and the private                 (SDWA), as amended in 1996, which
                                       repayment terms of up to 20 years.                      sector. Under section 202 of the UMRA,                 directs EPA to promulgate a national
                                       States prioritize funding based on                      EPA generally must prepare a written                   primary drinking water regulation for a
                                       projects that address the most serious                  statement, including a cost-benefit                    contaminant if EPA determines that the
                                       risks to human health and assist PWSs                   analysis, for proposed and final rules                 contaminant may have an adverse effect
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                                       most in need. Congress provided the                     with ‘‘Federal mandates’’ that may                     on the health of persons, occurs in
                                       DWSRF program $8 billion for fiscal                     result in expenditures to State, local and             PWSs with a frequency and at levels of
                                       years 1997 through 2004.                                Tribal governments, in the aggregate, or               public health concern, and regulation
                                          The DWSRF places an emphasis on                      to the private sector, of $100 million or              presents a meaningful opportunity for
                                       small and disadvantaged communities.                    more in any one year. Before                           health risk reduction.

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                                         Section VI of this preamble discusses                                  Stage 2 DBPR. Details are presented in
                                       the cost and benefits associated with the                                the Economic Analysis (USEPA 2005a).

                                                                                                                                                                                    Percent of 3%       Percent of 7%
                                                                                                                                     3% discount rate        7% discount rate      grand total costs   grand total costs
                                                                                                                                                                                      (percent)           (percent)

                                       Surface Water Systems Costs ................................................                               $41.4                  $41.2                    53                  54
                                       Ground Water Systems Costs .................................................                                20.3                   19.2                    26                  25
                                       State Costs ..............................................................................                   1.7                    1.7                     2                   2
                                       Tribal Costs ..............................................................................                  0.4                    0.4                     1                   0
                                            Total Public .......................................................................                   63.8                   62.5                    81                  81
                                       Surface Water Systems Costs ................................................                                 6.4                    6.3                     8                   8
                                       Ground Water Systems Costs .................................................                                 8.5                    8.0                    11                  10
                                            Total Private .....................................................................                    15.0                   14.3                    19                  19
                                                Grand total .................................................................                      78.8                   76.8                   100                 100
                                          Note: Detail may not add due to independent rounding. Estimates are discounted to 2003 and given in 2003 dollars.
                                          Source: Exhibits 3.2 and 7.5, USEPA 2005a.

                                          To meet the UMRA requirement in                                       E. Executive Order 13132: Federalism                      F. Executive Order 13175: Consultation
                                       section 202, EPA analyzed future                                                                                                   and Coordination With Indian Tribal
                                       compliance costs and possible                                               Executive Order 13132, entitled                        Governments
                                       disproportionate budgetary effects. The                                  ‘‘Federalism’’ (64 FR 43255, August 10,
                                                                                                                                                                             Executive Order 13175, entitled
                                       Agency believes that the cost estimates                                  1999), requires EPA to develop an
                                                                                                                                                                          ‘‘Consultation and Coordination with
                                       and regulatory alternatives indicated                                    accountable process to ensure                             Indian Tribal Governments’’ (65 FR
                                       earlier and discussed in more detail in                                  ‘‘meaningful and timely input by State                    67249, November 9, 2000), requires EPA
                                       section VI of this preamble, accurately                                  and local officials in the development of                 to develop ‘‘an accountable process to
                                       characterize future compliance costs of                                  regulatory policies that have federalism                  ensure meaningful and timely input by
                                       today’s rule.                                                            implications.’’ ‘‘Policies that have                      tribal officials in the development of
                                                                                                                federalism implications’’ is defined in                   regulatory policies that have tribal
                                          In analyzing disproportionate
                                       impacts, EPA considered the impact on                                    the Executive Order to include                            implications.’’ Under Executive Order
                                       (1) different regions of the United States,                              regulations that have ‘‘substantial direct                13175, EPA may not issue a regulation
                                       (2) State, local, and Tribal governments,                                effects on the States, on the relationship                that has Tribal implications, that
                                       (3) urban, rural and other types of                                      between the national government and                       imposes substantial direct compliance
                                       communities, and (4) any segment of the                                  the States, or on the distribution of                     costs, and that is not required by statute,
                                       private sector. This analysis is presented                               power and responsibilities among the                      unless the Federal government provides
                                                                                                                various levels of government.’’                           the funds necessary to pay the direct
                                       in Chapter 7of the Economic Analysis
                                                                                                                                                                          compliance costs incurred by Tribal
                                       (USEPA 2005a). EPA analyzed four                                            This final rule does not have
                                                                                                                                                                          governments, or EPA consults with
                                       regulatory alternatives and selected the                                 federalism implications. It will not have
                                                                                                                                                                          Tribal officials early in the process of
                                       least costly of these in accordance with                                 substantial direct effects on the States,                 developing the proposed regulation and
                                       UMRA Section 205.                                                        on the relationship between national                      develops a Tribal summary impact
                                          EPA has determined that the Stage 2                                   government and the States, or on the                      statement.
                                       DBPR contains no regulatory                                              distribution of power and                                    EPA has concluded that this final rule
                                       requirements that might significantly or                                 responsibilities among various levels of                  may have Tribal implications, because it
                                       uniquely affect small governments. The                                   government, as specified in Executive                     may impose substantial direct
                                       Stage 2 DBPR affects all size systems. As                                Order 13132. The final rule has one-                      compliance costs on Tribal
                                       described in section VII.C, EPA has                                      time costs for implementation of                          governments, and the Federal
                                       certified that today’s rule will not have                                approximately $7.8 million. Thus,                         government will not provide the funds
                                       a significant economic impact on a                                       Executive Order 13132 does not apply                      necessary to pay those costs.
                                       substantial number of small entities.                                    to this rule.                                                Accordingly, EPA provides the
                                       Average annual expenditures for small                                                                                              following Tribal summary impact
                                                                                                                   Although section 6 of Executive Order                  statement as required by section 5(b).
                                       CWSs to comply with the Stage 2 DBPR                                     13132 does not apply to this rule, in the
                                       range from $27.7 to $26.1 million at a                                                                                             EPA provides further detail on Tribal
                                                                                                                spirit of Executive Order 13132, and                      impact in the Economic Analysis
                                       3 and 7 percent discount rate,                                           consistent with EPA policy to promote                     (USEPA 2005a). Total Tribal costs are
                                       respectively.                                                            communications between EPA and State                      estimated to be approximately $391,773
                                          Consistent with the intergovernmental                                 and local governments, EPA nonetheless                    per year (at a 3 percent discount rate)
                                       consultation provisions of section 204 of                                specifically solicited comment on the                     and this cost is distributed across 755
                                       the UMRA and Executive Order 12875,                                      proposed rule from State and local                        Tribal systems. The cost for individual
                                       ‘‘Enhancing the Intergovernmental                                        officials and did consult with State and                  systems depend on system size and
                                       Partnership,’’ EPA has already initiated                                 local officials in developing this rule. A                source water type. Of the 755 Tribes that
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                                       consultations with the governmental                                      description of that consultation can be                   may be affected in some form by the
                                       entities affected by this rule. The                                      found in the preamble to the proposed                     Stage 2 DBPR, 654 use ground water as
                                       consultations are described in the                                       rule, 68 FR 49548, (August 18, 2003).                     a source and 101 systems use surface
                                       proposed rule (68 FR 49654, August 18,                                                                                             water or GWUDI. Since the majority of
                                       2003).                                                                                                                             Tribal systems are ground water systems

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                                       serving fewer than 500 people,                          H. Executive Order 13211: Actions                      suppliers is possible with the available
                                       approximately 15.6 percent of all Tribal                Concerning Regulations That                            data. The approach used to estimate the
                                       systems will have to conduct an IDSE.                   Significantly Affect Energy Supply,                    impact of energy use, therefore, focuses
                                       As a result, the Stage 2 DBPR is most                   Distribution, or Use                                   on national-level impacts. The analysis
                                       likely to have an impact on Tribes using                   This rule is not a ‘‘significant energy             estimates the additional energy use due
                                       surface water or GWUDI serving more                     action’’ as defined in Executive Order                 to the Stage 2 DBPR and compares that
                                       than 500 people.                                        13211, ‘‘Actions Concerning Regulations                analysis to the national levels of power
                                                                                               That Significantly Affect Energy Supply,               generation in terms of average and peak
                                          EPA consulted with Tribal officials                                                                         loads.
                                       early in the process of developing this                 Distribution, or Use’’ (66 FR 28355, May
                                                                                                                                                         The first step in the analysis is to
                                       regulation to permit them to have                       22, 2001) because it is not likely to have
                                                                                                                                                      estimate the energy used by the
                                       meaningful and timely input into its                    a significant adverse effect on the
                                                                                                                                                      technologies expected to be installed as
                                       development. Moreover, in the spirit of                 supply, distribution, or use of energy.
                                                                                                                                                      a result of the Stage 2 DBPR. Energy use
                                       Executive Order 13175, and consistent                   This determination is based on the                     is not directly stated in Technologies
                                                                                               following analysis.                                    and Costs for the Final Long Term 2
                                       with EPA policy to promote
                                                                                                  The first consideration is whether the
                                       communications between EPA and                                                                                 Enhanced Surface Water Treatment Rule
                                                                                               Stage 2 DBPR would adversely affect the
                                       Tribal governments, EPA specifically                                                                           and Final Stage 2 Disinfectants and
                                                                                               supply of energy. The Stage 2 DBPR
                                       solicited comment on the proposed rule                                                                         Disinfection Byproducts Rule (USEPA
                                                                                               does not regulate power generation,                    2005g), but the annual cost of energy for
                                       from Tribal officials.                                  either directly or indirectly. The public              each technology addition or upgrade
                                          As required by section 7(a), EPA’s                   and private utilities that the Stage 2                 necessitated by the Stage 2 DBPR is
                                       Tribal Consultation Official has certified              DBPR regulates do not, as a rule,                      provided. An estimate of plant-level
                                       that the requirements of the Executive                  generate power. Further, the cost                      energy use is derived by dividing the
                                       Order has been met in a meaningful and                  increases borne by customers of water                  total energy cost per plant for a range of
                                       timely manner. A copy of this                           utilities as a result of the Stage 2 DBPR              flows by an average national cost of
                                       certification has been included in the                  are a low percentage of the total cost of              electricity of $0.076/ kilowatt hours per
                                       docket for this rule.                                   water, except for a very few small                     year (kWh/yr) (USDOE 2004a). These
                                                                                               systems that might install advanced                    calculations are shown in detail in the
                                       G. Executive order 13045: Protection of                 technologies that must spread that cost                Economic Analysis (USEPA 2005a). The
                                       Children From Environmental Health                      over a narrow customer base. Therefore,                energy use per plant for each flow range
                                       Risks and Safety Risks                                  the customers that are power generation                and technology is then multiplied by
                                                                                               utilities are unlikely to face any                     the number of plants predicted to install
                                          Executive Order 13045: ‘‘Protection of               significant effects as a result of the Stage
                                       Children from Environmental Health                                                                             each technology in a given flow range.
                                                                                               2 DBPR. In sum, the Stage 2 DBPR does                  The energy requirements for each flow
                                       Risks and Safety Risks’’ (62 FR 19885,                  not regulate the supply of energy, does
                                       April 23, 1997) applies to any rule that:                                                                      range are then added to produce a
                                                                                               not generally regulate the utilities that              national total. No electricity use is
                                       (1) is determined to be ‘‘economically                  supply energy, and is unlikely
                                       significant’’ as defined under 12866,                                                                          subtracted to account for the
                                                                                               significantly to affect the customer base              technologies that may be replaced by
                                       and; (2) concerns an environmental                      of energy suppliers. Thus, the Stage 2                 new technologies, resulting in a
                                       health or safety risk that EPA has reason               DBPR would not translate into adverse                  conservative estimate of the increase in
                                       to believe may have a disproportionate                  effects on the supply of energy.                       energy use. The incremental national
                                       effect on children. If the regulatory                      The second consideration is whether                 annual energy usage is 0.12 million
                                       action meets both criteria, the Agency                  the Stage 2 DBPR would adversely affect                megawatt-hours (MWh).
                                       must evaluate the environmental health                  the distribution of energy. The Stage 2                   According to the U.S. Department of
                                       or safety effects of the planned rule on                DBPR does not regulate any aspect of                   Energy’s Information Administration,
                                       children, and explain why the planned                   energy distribution. The utilities that are            electricity producers generated 3,848
                                       regulation is preferable to other                       regulated by the Stage 2 DBPR already                  million MWh of electricity in 2003
                                       potentially effective and reasonably                    have electrical service. As derived later              (USDOE 2004b). Therefore, even using
                                       feasible alternatives considered by the                 in this section, the final rule is projected           the highest assumed energy use for the
                                       Agency.                                                 to increase peak electricity demand at                 Stage 2 DBPR, the rule when fully
                                          While this final rule is not subject to              water utilities by only 0.009 percent.                 implemented would result in only a
                                                                                               Therefore, EPA estimates that the                      0.003 percent increase in annual average
                                       the Executive Order because it is not
                                                                                               existing connections are adequate and                  energy use.
                                       economically significant as defined in
                                                                                               that the Stage 2 DBPR has no                              In addition to average energy use, the
                                       Executive Order 12866, EPA
                                                                                               discernable adverse effect on energy                   impact at times of peak power demand
                                       nonetheless has reason to believe that                  distribution.                                          is important. To examine whether
                                       the environmental health or safety risk                    The third consideration is whether                  increased energy usage might
                                       (i.e., the risk associated with DBPs)                   the Stage 2 DBPR would adversely affect                significantly affect the capacity margins
                                       addressed by this action may have a                     the use of energy. Because some                        of energy suppliers, their peak season
                                       disproportionate effect on children. EPA                drinking water utilities are expected to               generating capacity reserve was
                                       believes that the Stage 2 DBPR will                     add treatment technologies that use                    compared to an estimate of peak
                                       result in greater risk reduction for                    electrical power, this potential impact is             incremental power demand by water
                                       children than for the general                           evaluated in more detail. The analyses                 utilities.
                                       population. The results of the                          that underlay the estimation of costs for                 Both energy use and water use peak
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                                       assessments are contained in Section                    the Stage 2 DBPR are national in scope                 in the summer months, so the most
                                       VI.I of this preamble and in the                        and do not identify specific plants or                 significant effects on supply would be
                                       Economic Analysis (USEPA 2005a). A                      utilities that may install treatment in                seen then. In the summer of 2003, U.S.
                                       copy of all documents has been placed                   response to the rule. As a result, no                  generation capacity exceeded
                                       in the public docket for this action.                   analysis of the effect on specific energy              consumption by 15 percent, or

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                          471

                                       approximately 160,000 MW (USDOE                         also approving EPA Method 552.3 for                    method may be used). EPA is approving
                                       2004b). Assuming around-the-clock                       HAA5, which also can be used to                        four standards for determining total
                                       operation of water treatment plants, the                measure three unregulated HAAs that                    chlorine (SM 4500–Cl E and SM 4500–
                                       total energy requirement can be divided                 are not included in the consensus                      Cl I, 1998, in the 20th Edition of
                                       by 8,760 hours per year to obtain an                    methods. The unregulated HAAs are                      Standard Methods for the Examination
                                       average power demand of 13.28 MW. A                     included in the EPA method because                     of Water and Wastewater and SM 4500–
                                       more detailed derivation of this value is               some water systems monitor for them in                 Cl E–00 and SM 4500–Cl I–00, 2000
                                       shown in the Economic Analysis                          order to better understand their                       available at http://
                                       (USEPA 2005a). Assuming that power                      treatment processes and provide greater                www.standardmethods.org). Two
                                       demand is proportional to water flow                    public health protection. EPA is                       standards for determining free chlorine
                                       through the plant and that peak flow                    approving two voluntary consensus                      are approved in today’s rule (SM 4500–
                                       can be as high as twice the average daily               standards for daily monitoring for                     Cl H, 1998, in the 20th Edition of
                                       flow during the summer months, about                    chlorite (Standard Method 4500–ClO2 E,                 Standard Methods for the Examination
                                       26.55 MW could be needed for                            1998, in the 20th Edition of Standard                  of Water and Wastewater and SM 4500–
                                       treatment technologies installed to                     Methods for the Examination of Water                   Cl H–00, 2000 available at http://
                                       comply with the Stage 2 DBPR. This is                   and Wastewater and Standard Method                     www.standardmethods.org). Today’s
                                       only 0.017 percent of the capacity                      4500–ClO2 E–00, 2000, available at                     action approves three voluntary
                                       margin available at peak use.                           http://www.standardmethods.org). EPA                   consensus standards for measuring
                                          Although EPA recognizes that not all                 Method 327.0, Revision 1.1 is also being               chlorine dioxide (4500–ClO2 D and
                                       areas have a 15 percent capacity margin                 approved for daily monitoring for both                 4500–ClO2 E, 1998, in the 20th Edition
                                       and that this margin varies across                                                                             of Standard Methods for the
                                                                                               chlorite and chlorine dioxide in order to
                                       regions and through time, this analysis                                                                        Examination of Water and Wastewater
                                                                                               provide an alternative to the titration
                                       reflects the effect of the rule on national                                                                    and 4500–ClO2 E–00, 2000 available at
                                                                                               procedure that is required in the
                                       energy supply, distribution, and use.                                                                          http://www.standardmethods.org). EPA
                                                                                               Standard Methods. EPA is approving a
                                       While certain areas, notably California,                                                                       is approving six standards for
                                                                                               method from American Society for
                                       have experienced shortfalls in                                                                                 determining TOC and DOC (SM 5310 B,
                                                                                               Testing and Materials International for
                                       generating capacity in the recent past, a                                                                      SM 5310 C, and SM 5310 D, 1998, in the
                                                                                               bromate, chlorite and bromide analyses
                                       peak incremental power requirement of                                                                          20th Edition of Standard Methods for
                                                                                               (ASTM D 6581–00, 2000, ASTM
                                       26.55 MW nationwide is not likely to                                                                           the Examination of Water and
                                       significantly change the energy supply,                 International. Annual Book of ASTM
                                                                                                                                                      Wastewater and SM 5310 B–00, SM
                                       distribution, or use in any given area.                 Standards, Volume 11.01, American
                                                                                                                                                      5310 C–00, and SM 5310 D–00, 2000
                                       Considering this analysis, EPA has                      Society for Testing and Materials
                                                                                                                                                      available at http://
                                       concluded that Stage 2 DBPR will not                    International, 2001 or any year
                                                                                                                                                      www.standardmethods.org). Two
                                       have any significant effect on the use of               containing the cited version of the
                                                                                                                                                      standards for determining UV254 are
                                       energy, based on annual average use and                 method may be used). EPA is also
                                                                                                                                                      approved in today’s rule (SM 5910 B,
                                       on conditions of peak power demand.                     approving three EPA methods (EPA
                                                                                                                                                      1998, in the 20th Edition of Standard
                                                                                               Methods 317.0 Revision 2.0, 321.8, and                 Methods for the Examination of Water
                                       I. National Technology Transfer and                     326.0) that provide greater sensitivity
                                       Advancement Act                                                                                                and Wastewater and SM 5910 B–00,
                                                                                               and selectivity for bromate than the                   2000 available at http://
                                          As noted in the proposed rule,                       ASTM consensus standard. These EPA                     www.standardmethods.org). EPA is also
                                       Section 12(d) of the National                           methods are required in order to                       approving EPA Method 415.3 Revision
                                       Technology Transfer and Advancement                     provide better process control for water               1.1 for the determination of TOC and
                                       Act of 1995 (‘‘NTTAA’’), Public Law                     systems using ozone in the treatment                   SUVA (DOC and UV254). This EPA
                                       104–113, section 12(d) (15 U.S.C. 272                   process and to allow for a reduced                     method contains method performance
                                       note) directs EPA to use voluntary                      monitoring option. EPA Methods 317.0                   data that are not available in the
                                       consensus standards in its regulatory                   Revision 2.0 and 326.0 can also be used                consensus standards.
                                       activities unless to do so would be                     to determine chlorite and bromide.                        Copies of the ASTM standards may be
                                       inconsistent with applicable law or                     Today’s action approves eight voluntary                obtained from the American Society for
                                       otherwise impractical. Voluntary                        consensus standards for determining                    Testing and Materials International, 100
                                       consensus standards are technical                       free, combined, and total chlorine (SM                 Barr Harbor Drive, West Conshohocken,
                                       standards (e.g., materials specifications,              4500–Cl D, SM 4500–Cl F, and 4500–Cl                   PA 19428–2959. The Standard Methods
                                       test methods, sampling procedures, and                  G, 1998, in the 20th Edition of Standard               may be obtained from the American
                                       business practices) that are developed or               Methods for the Examination of Water                   Public Health Association, 1015
                                       adopted by voluntary consensus                          and Wastewater and SM 4500–Cl D–00,                    Fifteenth Street, NW., Washington, DC
                                       standard bodies. The NTTAA directs                      SM 4500–Cl F–00, and 4500–Cl G–00,                     20005.
                                       EPA to provide Congress, through OMB,                   2000 available at http://
                                       explanations when the Agency decides                    www.standardmethods.org and ASTM D                     J. Executive Order 12898: Federal
                                       not to use available and applicable                     1253–86(96), 1996, ASTM International,                 Actions To Address Environmental
                                       voluntary consensus standards.                          Annual Book of ASTM Standards,                         Justice in Minority Populations or Low-
                                          This rulemaking involves technical                   Volume 11.01, American Society for                     Income Populations
                                       standards. EPA has decided to use two                   Testing and Materials International,                      Executive Order 12898 establishes a
                                       voluntary consensus methods for HAA5                    1996 or any year containing the cited                  Federal policy for incorporating
                                       (Standard Method 6251 B, 1998 in the                    version of the method may be used and                  environmental justice into Federal
                                       20th Edition of Standard Methods for                    ASTM D 1253–03, 2003, ASTM                             agency missions by directing agencies to
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                                       the Examination of Water and                            International, Annual Book of ASTM                     identify and address disproportionately
                                       Wastewater and Standard Method 6251                     Standards, Volume 11.01, American                      high and adverse human health or
                                       B–94, 1994 available at http://                         Society for Testing and Materials                      environmental effects of its programs,
                                       www.standardmethods.org). In addition                   International, 2004 or any year                        policies, and activities on minority and
                                       to these two consensus methods, EPA is                  containing the cited version of the                    low-income populations. EPA has

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                                       472               Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations

                                       considered environmental justice                        analysis is described in more detail and               large systems. The capacity of systems
                                       related issues concerning the potential                 can be found in the Economic Analysis                  that must conduct an operational
                                       impacts of this action and consulted                    (USEPA 2005a). Analyses reflect only                   evaluation will only be impacted in a
                                       with minority and low-income                            the impact of new or revised                           minor way, while those systems that
                                       stakeholders. A description of this                     requirements, as established by the                    must only familiarize themselves with
                                       consultation can be found in the                        LT2ESWTR; the impacts of previously                    the rule (the large majority of systems)
                                       proposed rule (USEPA 2003a).                            established requirements on system                     will not face any capacity impact as a
                                                                                               capacity are not considered.                           result of the Stage 2 DBPR.
                                       K. Consultations With the Science                          EPA has defined overall water system
                                       Advisory Board, National Drinking                       capacity as the ability to plan for,                   N. Congressional Review Act
                                       Water Advisory Council, and the                         achieve, and maintain compliance with
                                       Secretary of Health and Human Services                                                                            The Congressional Review Act, 5
                                                                                               applicable drinking water standards.                   U.S.C. 801 et seq., as added by the Small
                                         In accordance with Section 1412(d)                    Capacity encompasses three                             Business Regulatory Enforcement
                                       and (e) of the SDWA, the Agency                         components: technical, managerial, and                 Fairness Act of 1996, generally provides
                                       consulted with the Science Advisory                     financial. Technical capacity is the                   that before a rule may take effect, the
                                       Board, the National Drinking Water                      physical and operational ability of a                  agency promulgating the rule must
                                       Advisory Council (NDWAC), and the                       water system to meet SDWA
                                                                                                                                                      submit a rule report, which includes a
                                       Secretary of Health and Human Services                  requirements. This refers to the physical
                                                                                                                                                      copy of the rule, to each House of the
                                       on today’s rule.                                        infrastructure of the water system,
                                                                                                                                                      Congress and to the Comptroller General
                                         EPA met with the SAB to discuss the                   including the adequacy of source water
                                                                                                                                                      of the United States. EPA will submit a
                                       Stage 2 DBPR on June 13, 2001                           and the adequacy of treatment, storage,
                                                                                                                                                      report containing this rule and other
                                       (Washington, DC), September 25–26,                      and distribution infrastructure. It also
                                                                                                                                                      required information to the U.S. Senate,
                                       2001 (teleconference), and December                     refers to the ability of system personnel
                                                                                                                                                      the U.S. House of Representatives, and
                                       10–12, 2001 (Los Angeles, CA). Written                  to adequately operate and maintain the
                                                                                                                                                      the Comptroller General of the United
                                       comments from the December 2001                         system and to otherwise implement
                                                                                                                                                      States prior to publication of the rule in
                                       meeting of the SAB addressing the                       requisite technical knowledge.
                                                                                               Managerial capacity is the ability of a                the Federal Register. A Major rule
                                       occurrence analysis and risk assessment
                                                                                               water system to conduct its affairs to                 cannot take effect until 60 days after it
                                       were generally supportive. SAB
                                                                                               achieve and maintain compliance with                   is published in the Federal Register.
                                       comments are discussed in greater detail
                                                                                               SDWA requirements. Managerial                          This action is a ‘‘major rule’’ as defined
                                       within the proposal.
                                         EPA met with the NDWAC on                             capacity refers to the system’s                        by 5 U.S.C. 804(2). This rule will be
                                       November 8, 2001, in Washington, DC                     institutional and administrative                       effective March 6, 2006.
                                       to discuss the Stage 2 DBPR proposal.                   capabilities. Financial capacity is a                  VIII. References
                                       The Advisory Committee generally                        water system’s ability to acquire and                  American Public Health Association (APHA).
                                       supported the need for the Stage 2 DBPR                 manage sufficient financial resources to                   1998. Twentieth Edition of Standard
                                       based on health and occurrence data,                    allow the system to achieve and                            Methods for the Examination of Water
                                       but also stressed the importance of                     maintain compliance with SDWA                              and Wastewater, American Public Health
                                       providing flexibility to the systems                    requirements.                                              Association, 1015 Fifteenth Street, NW.,
                                       implementing the rule. The results of                      EPA estimated the impact of the Stage                   Washington, DC 20005.
                                       these discussions are included in the                   2 DBPR on small and large system                       Aschengrau, A., S. Zierler and A. Cohen.
                                       docket for the proposed rule.                           capacity as a result of the measures that                  1989. Quality of Community Drinking
                                                                                               systems are expected to adopt to meet                      Water and the Occurrence of
                                       L. Plain Language                                       the requirements of the rule (e.g.,                        Spontaneous Abortions. Arch. Environ.
                                                                                                                                                          Health. 44:283–90.
                                          Executive Order 12866 requires each                  selecting monitoring sites for the IDSE,               Aschengrau, A., S. Zierler and A. Cohen.
                                       agency to write its rules in plain                      installing/upgrading treatment, operator                   1993. Quality of Community Drinking
                                       language. Readable regulations help the                 training, communication with regulators                    Water and the Occurrence of Late
                                       public find requirements quickly and                    and the service community, etc.). The                      Adverse Pregnancy Outcomes. Arch.
                                       understand them easily. They increase                   Stage 2 DBPR may have a substantial                        Environ. Health. 48:105–113.
                                       compliance, strengthen enforcement,                     impact on the capacity of the 1,743                    ATSDR. 1997a. Toxicological profile for
                                       and decrease mistakes, frustration,                     plants in small systems and 518 plants                     tetrachloroethylene (PERC). Agency for
                                       phone calls, appeals, and distrust of                   in large systems that must make changes                    Toxic Substances and Disease Registry,
                                       government. EPA made every effort to                    to their treatment process to meet the                     Atlanta, GA. U.S. Department of Health
                                       write this preamble to the final rule in                Stage 2 DBPR requirements. However,                        and Human Services, Public Health
                                       as clear, concise, and unambiguous                      while the impact to these systems is
                                                                                                                                                      ATSDR. 1997b. Toxicological profile for
                                       manner as possible.                                     potentially significant, only 3.8 percent                  trichloroethylene (TCE). Agency for
                                                                                               of all plants regulated under the Stage                    Toxic Substances and Disease Registry,
                                       M. Analysis of the Likely Effect of                     2 DBPR (2,261 of 60,220) will be
                                       Compliance With the Stage 2 DBPR on                                                                                Atlanta, GA. U.S. Department of Health
                                                                                               affected by this requirement. Since                        and Human Services, Public Health
                                       the Technical, Managerial, and                          individual systems may employ more                         Service.
                                       Financial Capacity of Public Water                      than one plant, it is likely that fewer                ATSDR. 2004. Toxicological profile for 1,1,1-
                                       Systems                                                 than 1,620 systems (3.4 percent of                         trichloroethane (Draft for Public
                                          Section 1420(d)(3) of SDWA, as                       48,293 systems) will be affected by this                   Comment). Agency for Toxic Substances
                                       amended, requires that, in promulgating                 requirement. The new IDSE and                              and Disease Registry, Atlanta, GA. U.S.
                                       a National Primary Drinking Water                                                                                  Department of Health and Human
                                                                                               monitoring requirements are expected to
                                                                                                                                                          Services, Public Health Service.
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                                       Regulation (NPDWR), the Administrator                   have a small impact on the technical                   Baribeau, H., S.W. Krasner, R. Chin, and P.C.
                                       shall include an analysis of the likely                 and managerial capacity of small                           Singer. 2000. Impact of Biomass on the
                                       effect of compliance with the regulation                systems, a moderate impact on the                          Stability of Haloacetic Acids and
                                       on the technical, managerial, and                       financial capacity of some small                           Trihalomethanes in a Simulated
                                       financial (TMF) capacity of PWSs. This                  systems, and a much smaller impact on                      Distribution System. Proc. of the Water

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                                                         Federal Register / Vol. 71, No. 2 / Wednesday, January 4, 2006 / Rules and Regulations                                                473

                                           Quality Technology Conference. Denver,              Cedergren, M.I., A.J. Selbing, O. Lofman, and          Dodds, L., W. King, A.C. Allen, B.A. Armson,
                                           CO.                                                              ¨ ´
                                                                                                   B.A.J. Kallen. 2002. Chlorination                       D.B. Deshayne, and C. Nimrod. 2004.
                                       Barrett, S., C. Hwang, Y.C. Guo, S.A.                       byproducts and nitrate in drinking water                Trihalomethanes in public water
                                           Andrews, and R. Valentine. 2003.                        and risk for congenital cardiac defects.                supplies and risk of stillbirth.
                                           Occurrence of NDMA in drinking waters.                  Environmental Research. 89(2):124–130.                  Epidemiology. 15(2):179–186.
                                           Proc. of the AWWA Annual Conference.                Chen, J., G.C. Douglas, T.L. Thirkill, P.N.            Doyle, T.J., W. Sheng, J.R. Cerhan, C.P. Hong,
                                           Annaheim, CA.                                           Lohstroh, S.R. Bielmeir, M.G. Narotsky,                 T.A. Sellers, L.H. Kushi, and A.R.
                                       Bielmeier, S.R., D.S. Best, D.L. Guidici, and               D.S. Best, R.A. Harrison, K. Natarajan,                 Folsom. 1997. The Association of
                                           M.G. Narotsky. 2001. Pregnancy Loss in                  R.A. Pegram, J.W. Overstreet and B.L.                   Drinking Water Source and Chlorination
                                           the Rat Caused by                                       Lasley. 2003. Effect of                                 By-Products with Cancer Incidence
                                           Bromodochloromethane. Toxicol Sci.                      bromodichloromethane on chorionic                       Among Postmenopausal Women in Iowa:
                                           59(2):309–15.                                           gonadotropin secretion by human                         A Prospective Cohort Study. American
                                       Bielmeier, S.R., D.S. Best and M.G. Narotsky.               placental trophoblast cultures.                         Journal of Public Health. 87(7).
                                           2004. Serum hormone characterization                    Toxicological Sciences. 76(1):75–82.               Fair, P.S., R.K. Sorrell and M. Stultz-
                                           and exogenous hormone rescue of                     Chen, J., T.L. Thirkill, P.N. Lohstroh, S.R.                Karapondo. 2002. Quality of Information
                                           bromodichloromethane-induced                            Bielmeir, M.G. Narotsky, D.S. Best, R.A.                Collection Rule Monitoring Data. In
                                           pregnancy loss in the F344 rat.                         Harrison, K. Natarajan, R.A. Pegram, J.W.               Information Collection Rule Data
                                           Toxicological Sciences. 77(1):101–108.                  Overstreet, B. L. Lasley and G.C.                       Analysis, M.J. McGuire, J. McLain, and
                                       Blake, N.M. 1956. Water for the Cities: A                   Douglas. 2004. Bromodichloromethane                     A. Obolensky (eds). AwwaRF. Denver,
                                           History of the Urban Water Supply                       inhibits human placental trophoblast                    CO.
                                           Problem in the United States. P. 263–                   differentiation. Toxicological Sciences.           Fenster, L., G.C. Windham, S.H. Swan, D.M.
                                           264. Syracuse University Press, New                     78(1):166–174.                                          Epstein, and R.R. Neutra. 1992. Tap or
                                           York.                                               Chevrier, C., B. Junod, and S. Cordier. 2004.               bottled water consumption and
                                       Bove, F.J., M.C. Fulcomer, J.B. Koltz, J.                   Does ozonation of drinking water reduce                 spontaneous abortion in a case-control
                                           Esmart, E.M. Dufficy and R.T.                           the risk of bladder cancer?                             study of reporting consistency.
                                           Zagraniski. 1992a. Report on phase IV–                  Epidemiology. 15(5):605–614.                            Epidemiology. 3:120–124.
                                           A: Public drinking water contamination              Christian, M.S., R.G. York, A.M. Hoberman,             Fenster, L., K. Waller, G. Windham, T.
                                           and birthweight fetal deaths, and birth                 L.C. Frazee, L.C. Fisher, W.R. Brown,                   Henneman, M. Anderson, P. Mendola,
                                           defects, a crosssectional study. New                    and D.M. Creasy. 2002a. Oral (drinking                  J.W. Overstreet and S.H. Swan. 2003.
                                           Jersey Dept. of Health.                                 water) Two Generation Reproductive                      Trihalomethane levels in home tap water
                                       Bove, F.J., M.C. Fulcomer, J.B. Koltz, J.                   Toxicity Study of Dibromoacetic Acid                    and semen quality. Epidemiology.
                                                                                                   (DBA) in Rats. International Journal of
                                           Esmart, E.M. Dufficy, R.T. Zagraniski                                                                           14:650–658.
                                                                                                   Toxicology. 21(4):237–76.
                                           and J.E. Savrin. 1992b. Report on Phase                                                                    Ferreira-Gonzalez, A., A.B. DeAngelo, S.
                                                                                               Christian M.S., R.G. York, A.M. Hoberman,
                                           IV–B: Public drinking water                                                                                     Nasim and C.T. Garrett. 1995. Ras
                                                                                                   R.M. Diener, and L.C. Fisher. 2002b. Oral
                                           contamination and birthweight and                                                                               Oncogene Activation during
                                                                                                   (drinking water) Two Generation
                                           selected birth defects, a case-control                                                                          Hepatocarcinogenesis in B6C3F1 Male
                                                                                                   Reproductive Toxicity Study of
                                           study. New Jersey Dept. of Health.                      Bromodichloromethane (BDCM) in Rats.                    Mice by Dichloroacetic and
                                       Bove, F.J., M.C. Fulcomer, J.B. Koltz, J.                   International Journal of Toxicology.                    Trichloroacetic Acids. Carcinogenesis.
                                           Esmart, E.M. Dufficy, R.T. Zagraniski                   21(2):115–146.                                          16(3):495–500.
                                           and J.E. Savrin. 1995. Public drinking              Craun G.C., ed. 1998. EPA Panel Report and             Freedman, M., K.P. Cantor, N.L. Lee, L.S.
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                                          00/007.                                              USEPA. 2003d. Technologies and Costs for                    of Total Organic Carbon and Specific UV
                                       USEPA. 2000d. Review of the EPA’s Draft                    Control of Microbial Pathogens and                       Absorbance at 254 nm in Source Water
                                          Chloroform Risk Assessment by a                         Disinfection Byproducts. Prepared by the                 and Drinking Water. Revision 1.1. EPA/
                                          Subcommittee of the Science Advisory                    Cadmus Group and Malcolm Pirnie.                         600/R–05/055. (Available at http://
                                          Board. Science Advisory Board,                       USEPA. 2003e. Draft Significant Excursion                   www.epa.gov/nerlcwww/ordmeth.htm.)
                                          Washington, DC. EPA–SAB–EC–00–009.                      Guidance Manual. Washington, DC.                    USEPA. 2005m. Unregulated Contaminant
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                                       USEPA. 2000f. Information Collection Rule                  Extraction, Derivatization, and Gas                      Request for National Primary Drinking
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                                          815–C–00–002, April 2000.                               Detection. Revision 1.0. EPA–815–B–03–                   Disinfectants and Disinfection
                                       USEPA. 2000g. Method 321.8. In Methods for                 002. (Available at http://www.epa.gov/                   Byproducts Rule. Washington, DC. EPA
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                                       USEPA. 2000h. Method 300.1. In Methods for                 Regulations; Analysis and Sampling                  USFDA (Food and Drug Administration).
                                          the Determination of Organic and                        Procedures; Proposed Rule. 66 FR 18166,                  1994. Sanitizing Solutions. 21 Code of
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                                          Volume 1. ORD–NERL, Cincinnati, OH.                  USEPA. 2005a. Economic Analysis for the                     178.1010.&http://ecfr.gpoaccess.gov/cgi/
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                                          Report. Prepared for Environmental                      Document for Brominated                                  review of epidemiological studies.
                                          Economics Advisory Committee. July 27,                  Trihalomethanes. Washington, DC. EPA                     Medicina Clinica 117(1): 27–35.
                                          2000. EPA–SAB–EEAC–00–013.                              822–R–05–011.                                            (Spanish).
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                                          EPA/635/R–01/001.                                    USEPA. 2005d. Drinking Water Addendum                       Consumption of Chlorinated Drinking
                                       USEPA. 2001b. Integrated Risk Information                  to the Criteria Document for                             Water and Bladder Cancer. Journal of
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                                          Bromate. Washington, DC: U.S. EPA.                      DC. EPA 822–R–05–008.                                    166–173.
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                                       USEPA. 2001c. Method 317.0. Determination                  the Criteria Document for Trichloroacetic                J.J.K. Jaakkola, W.D. King, C.F. Lynch, S.
                                          of Inorganic Oxyhalide Disinfection By-                 Acid. Washington, DC. EPA 822–R–05–                      Porru and M. Kogevinas. 2004.
                                          Products in Drinking Water Using Ion                    010.                                                     Disinfection byproducts and bladder
                                          Chromatography with the Addition of a                USEPA. 2005f. Occurrence Assessment for                     cancer a pooled analysis. Epidemiology.
                                          Postcolumn Reagent for Trace Bromate                    the Final Stage 2 Disinfectants and                      15(3):357–367.
                                          Analysis. Revision 2.0. EPA 815–B–01–                   Disinfection Byproducts Rule.                       Vinceti, M., G. Fantuzzi, L. Monici, et al.
                                          001. (Available at http://www.epa.gov/                  Washington, DC. EPA 815–R–05–011.                        2004. A retrospective cohort study of
                                          safewater/methods/sourcalt.html.)                    USEPA. 2005g. Technologies and Costs for                    trihalomethane exposure through
                                       USEPA. 2001d. Arsenic Rule Benefits                        the Final Long Term 2 Enhanced Surface                   drinking wate