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The Distribution, Transport and Cycling of Dissolved UNIVERSITY
and Particulate Organic Carbon in the Potomac and OF THE
Anacostia Rivers in the Greater Washington Area DISTRICT OF COLUMBIA
WRRC Report 13
THE DISTRIBUTION, TRANSPORT AND CYCLING
OF DISSOLVED AND PARTICULATE ORGANIC
CARBON IN THE POTOMAC AND ANACOSTIA
RIVERS IN THE GREATER WASHINGTON AREA
BY
Michael A. Champ
Department of Biology
The American University
Washington, D.C. 20016
FINAL REPORT
Project No. A00-2-DC-Phase I
Annual Allotment No. 14-31-001-50502
District of Columbia Water Resources
Research Center
University of the District of Columbia
Van Ness Campus
Dr. Mamadou H. Watt, Director
This research has been conducted in accordance
with Public Law 88-379, The Water Resources
Research Act of 1964 under the auspices of the
Director, Office of Water Research and
Technology, U.S. Department of the Interior.
November, 1979
ABSTRACT
Dissolved and particulate organic carbon concentrations have been determined for weekly
sampling of seventeen main channel stations of the Upper Potomac River Estuary. The distribution,
production, transport and cycling of organic carbon has been followed for twelve months. Special
studies have been conducted to evaluate the influence of tidal activities, flood storm crests and
lateral variation on DOC and POC concentrations in the River.
Major sources in the Washington, D.C. area have been compared (storm and combined
sewers, sanitary sewers, street runoff, shopping center parking lot runoff, residential and industrial
areas, Rock Creek and the Anacostia River) to the Potomac River background levels for DOC and.
POC.
Key words: Potomac River, Washington D.C.; dissolved (DOC) and particulate (POC)
organic carbon; DOC:POC ratios; municipal and industrial water
pollution; storm and combined sewers; street runoff; point and non-point
sources
-i-
ACKNOWLEDGEMENTS
This research project has been funded for $13,702 by Memorandum of Agreement,
dated January 23, 1975 from the Annual Allotment Funds of the District of Columbia
Water Resources Research Center, University of the District of Columbia, Washington,
D.C. Dr. James S. Burton was Director of the Center for the first part of the project and Dr.
Robert R. Bradford, Director of the Experiment Station, has served as Acting Director for
the duration of the project.
Mr. Bruce M. Bortz, the Project Manager is to be acknowledged and praised for his
expertise in coordinating the logistics of an extensive bad weather sampling project for rivers,
streams, storm runoff, combined sewer and storm sewers throughout the year and for the
laboratory analysis of. water samples. Ann E. Roffman, Douglas A. Hornbeck and
Howard M. Kingston are to be acknowledged for assisting in the sample collection. Special
acknowledgement is extended to the Water Resources Management Administration of D.C.
Environmental Services, especially Harold M. Stern and Jack Breem. Mr. Breem, the combined
sewer Project Manager, was extremely helpful in designing the overflow sampling project. The
typists for this report have been Ann E. Hoffman, Sheila A. Besse and Tommie R. Champ.
Tommie Champ is also to be thanked for final drafting of figures.
This report is submitted to The District of Columbia Water Resources Research Center as
required by Memorandum of Agreement for Project No. A-002-DC. A second Project No. A-
004-DC has been conducted investigating organic carbon, organic nitrogen and organic
phosphorus relationships in combined and storm sewers in the Washington, D.C. area. The
project report is in preparation at this time.
-ii-
TABLE OF CONTENTS
ABSTRACT................................................................... i.
ACKNOWLEDGEMENTS............................................ ii.
LIST OF TABLES........................................................ iv.
LIST OF FIGURES...................................................... vi.
INTRODUCTION.......................................................... 1.
METHODS AND MATERIALS.................................... 5.
RESULTS AND DISCUSSION.................................... 12.
SUMMARY................................................................. 41.
CONCLUSIONS.......................................................... 42.
RECOMMENDATIONS.............................................. 43.
REFERENCES CITED................................................. 44.
APPENDIX................................................................. 47.
-iii-
LIST OF TABLES
Monthly mean values of dissolved organic carbon
Table 1. (DOC) concentrations (mg C/liter) for Potomac and -13-
Anacostia Rivers for indicated stations.
Monthly mean values of particulate organic carbon
Table 2. (POC) concentrations (mg C/liter) for Potomac and -14-
Anacostia Rivers for indicated stations.
Percent change in seasonal means for selected
Table 3. stations and seasons for DOC and POC for indicated -18-
stations.
Appendix
Listing and location of current and proposed overflow
structures located on the Potomac River Watershed in
the Greater Washington, D.C. area, with the discharge
Table 1. receiving waters and frequency of occurence. Source: -61-
The District of Columbia's National Polutant Discharge
Permint (No. D000121199) from the U.S.E.P.A., Region
III, for the period of June 30, 1974 to June 30, 1979.
Dissolved (DOC) and particulate (POC) organic carbon
Table 2. concentrations (mg C/liter) for Chain Bridge station -65-
for indicated dates and depths.
Dissolved (DOC) and particulate (POC) organic carbon
Table 3. concentrations (mg/ C/liter) for Key Bridge station -67-
for indicated dates and depths.
Dissolved (DOC) and particulate (POC) organic carbon
Table 4. concentrations (mg C/liter) for Memorial Bridge station -69-
for indicated dates and depths.
Dissolved (DOC) and particulate (POC) organic carbon
Table 5. concentrations (mg C/liter) for 14th Street Bridge -71-
station for indicated dates and depths.
Dissolved (DOC) and particulate (POC) organic carbon
Table 6. concentrations (mg C/liter) for Anacostia River -73-
station for indicated dates and depths.
Dissolved (DOC) and particulate (POC) organic carbon
Table 8. concentrations (mg C/liter) for Wilson Bridge station -76-
for indicated dates and depths.
Dissolved (DOC) and particulate (POC) organic carbon
Table 9. concentrations (mg C/liter ) for Buoy 84 station -78-
for indicated dates and depths.
Total (TOC), dissolved (DOC) and particulate (POC)
organic carbon concentrations (mg C/liter) in
Table 10. -79-
surface water samples collected from indicated Potomac
River stations on February 15,. 1976.
Surface water monitoring of dissolved (DOC), part
iculate (POC) and total (TOC) organic carbon concentrations (mg
Table 11. -81-
C/liter) for Chain Bridge station for September 26, 1975 to September
28, 1975.
List of Tables - Appendix continued
Suspended sediment analysis of Chain Bridge station surface
Table 12. water samples obtained on September 26, 1975 to September 28, -82-
1975.
Twenty-four hour monitoring of dissolved (DOC) and
Table 13. particulate (POC) organic carbon concentrations (mg C/liter) for -83-
Memorial Bridge station on June 24, 1975 to June 25, 1975.
Transect of dissolved (DOC) and particulate (POC)
Table 14. organic carbon concentrations (mg C/liter) for the -85-
Potomac River at Memorial Bridge station on June 24, 1975.
Flow data of dissolved (DOC) and particulate (POC)
Table 15. organic carbon concentrations (mg C/liter) for -86-
indicated Rock Creek stations for indicated dates.
Street runoff data of dissolved (DOC) and particulate (POC)
Table 16. organic carbon concentrations (mg C/liter) for indicated Falls -87-
Church, Virginia stations for indicated dates.
Storm sewer dissolved (DOC) and particulate (POC)
Table 17. organic carbon concentrations (mg C/liter) for -88-
Garfield Street station for indicated dates.
Land runoff data of dissolved (DOC) and particulate (POC)
Table 18. organic carbon concentrations (mg C/liter) for indicated -88-
Washington, D.C. stations for February 18, 1976.
Storm sewer dissolved (DOC) and particulate (POC)
Table 19. organic carbon concentrations (mg C/liter) for -89-
New Mexico Avenue station for indicated dates.
Storm sewer dissolved (DOC) and particulate (POC)
Table 20. organic carbon concentrations (mg C/liter) for -90-
New York Avenue station for indicated dates.
Dry flow (no overflow) concnentrations of dissolved
Table 21. (DOC) and particulate (POC) organic carbon (mg/1) -91-
for indicated combined sewer stations for indicated dates.
Overflow data of dissolved_(DOC) and particulate
Table 22. (POC) organic carbon concentrations (mg C/liter) -92-
for indicated combined sewer stations for indicated dates.
Time of water sample collection for indicated
Table 23. -93-
stations for indicated dates.
Daily precipitation data for Washington, D.C.
Table 24. -96-
National Airport for February 1975 to February 1976.
Miscellaneous physical data from the Little Falls,
Table 25. Maryland station of the Potomac River for the -98-
sampling dates of the study period.
Times of high and low waters for indicated Potomac River and
Table 26. -100-
Anacostia River stations for indicated dates.
LIST OF FIGURES
Figure 1. Schematic system drawing rainfall through overflow
-3-
(from Field and Tafuri, 1973).
Figure 2. Station locations on the Potomac and Anacostia Rivers. -6-
Figure 3. Flow chart for organic carbon analysis (DOC and
-10-
POC) (Champ, 1973).
Figure 4. Monthly station means of dissolved organic carbon (mg/1) for
-15-
indicated stations on the Potomac and Anacostia Rivers.
Figure 5. Monthly station means of particulate organic carbon (mg/1) for
-16-
indicated stations on the Potomac and Anacostia Rivers.
Figure 6. Dissolved (DOC) and Particulate (POC) organic carbon
concentrations (mg/1) for indicated Potomac River stations for -21-
February 15, 1976.
Figure 7. Concentrations (mg/1) of dissolved (DOC) and particulate (POC)
organic carbon and suspended sediment in water samples
-22-
collected from Chain Bridge before, during, and after a crest in
the Potomac River between September 26 to 28, 1975.
Figure 8. Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg/1) in water samples collected from the Chain -23-
Bridge station on the Potomac River for indicated dates.
Figure 9. Mean dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg/1) in mid channel Potomac River water
samples collected hourly at surface, middle, and bottom depths -24-
from Arlington Memorial Bridge for a 25 hour period, June 24 and
25, 1975.
Figure 10. Mean total (TOC), dissolved(DOC) and particulate (POC) organic
carbon concentrations (mg/1) of water samples collected at
surface, middle, and bottom depths for 100 foot intervals in a Iran -25-
sect across the Potomac River from Memorial Bridge on June 24,
1975.
Figure 11. Comparison of mean dissolved (DOC) and particulate (POC)
organic carbon concentrations (mg/1) for indicated combined and
-27-
storm sewers to Potomac River annual and storm means with
DOC:POC ratios.
Figure 12. Comparison of mean dissolved (DOC) and particulate (POC)
organic carbon concentrations (mg/1) for street runoff
-28-
(residential), shopping center parking lot runoff, and park land
runoff for indicated dates.
Figure 13. Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg/1) in water samples collected
-30-
from the Garfield Street storm sewer overflow on
July 9, 1975.
List of Figures (continued)
Figure 14. Dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg/1) in water samples collected from the New Mexico Avenue storm sewer
overflow on July 9, 1975. -31-
Figure 15. Dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg/1) in water samples collected from the New Mexico Avenue
storm sewer overflow on July 10, 1975. -32-
Figure 16. Dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg/1) in water samples collected from the New Mexico Avenue
storm sewer overflow on February 22, 1976. -33-
Figure 17. Dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg/1) in water samples collected from the New York Avenue storm
sewer overflow on February 13, 1975. -34-
Figure 18. Dissolved organic carbon concentrations (mg/1) in
water samples collected from the industrial and residential branches
of the New York Avenue storm sewer overflow on February 22, 1975. -35-
Figure 19. Particulate organic carbon concentrations (mg/1) in water samples collected
from the industrial and residential branches of the New York Avenue
storm sewer overflow on February 22, 1975. -36-
Figure 20. Dissolved organic carbon concentrations (mg/1) in water samples collected
from the industrial and residential branches of the New York Avenue storm
sewer overflow on March 5, 1975. -37-
Figure 21. Particulate organic carbon concentrations (mg/1) in
water samples collected from the industrial and residential branches of
the New York Avenue storm sewer overflow on March 5, 1975. -38-
Figure 22. Dissolved (DOC) and particulate (POC) organic carbon concentrations (mg/1)
in water samples collected from indicated combined sewers on June 10, 1975. -39-
Figure 23. Dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg/1) in water samples collected from indicated combined sewers
on February 27, 1976. -40-
Appendix
Figure 1. Storm sewer sampling site for Garfield Street. -50-
Figure 2. Storm sewer sampling site for New Mexico Avenue. -51-
Figure 3. Combined sewer sampling site of Easby Point (DES #34). -54-
Figure 4. Combined sewer sampling site for the Potomac River
Pumping Station (DES #35). -55-
Figure 5. Combined sewer sampling site for 30th and K Streets
(DES #38A). -57-
Figure 6. Combined sewer sampling site for Potomac River and
Water Streets (DES 443). -59-
INTRODUCTION
Carbon, the backbone of organic compounds, forms an essential link in the interaction
between the inorganic environment and living organisms. Despite its importance, the chemistry of
aqueous organic matter is one of the least well-known sections in the chemistry of natural waters
(Duursma, 1965).
The process of eutrophication is causing an ecological crisis in many bodies of water
throughout the world. Champ (1975) defined eutrophication as the buildup of rapidly cycled
organic carbon. To better understand this process, rational models for water quality management
will have to be developed. This requires a fuller qualitative and quantitative understanding of the
interactions of chemical, physical and biological events occuring in natural waters.
The relationships of various forms of inorganic carbon (C02, HC03, and C02) have been
understood for many years because analytical procedures have been available to establish them.
However, prior to recent develop ments, the methods of analysis for organic carbon have been
tedious. Instrumentation is now available which permits quantitative analysis of dissolved (DOC)
and particulate (POC) organic carbon in water. The distribution of organic carbon in the marine
environment has been studied in the last decade by many researchers (Duursma, 1961, 1963;
Parsons and Strickland, 1961; Menzel, 1964, 1967; Sutcliffe, Baylor and Menzel, 1963; Menzel
and Vaccaro, 1964; Fredericks, 1968; and Fredericks and Sackett, 1970). A few values for DOC
and POC in inland waters, determined by means of infrared analysis of organic carbon oxidized to
C02 have been published.
Coastal (Tidal) River Studies
There have been a few studies of organic carbon in Texas inland waters. Wilson (1963)
reported values for Texas.rivers and bays (Brazos, Colorado, Guadalup e, San Marcos and San
Antonio). He found that organic carbon in rivers generally increased as they flow to the coast.
Fredricks and Sackett (1970) have reported on the contribution of the Brazos River to the organic
carbon levels in the Gulf of Mexico. Brooks (1970) reported on the distribution of organic carbon
in the Brazos River Basin. Parker and Calder (1968) studied organic carbon in the Guadalupe
River, Corpus Christi Bay and in the Houston Ship Channel. Weber and Moore (1967) have
reported values for organic carbon in the Little Miami River, near Cincinnati, Ohio. Brooks (1970)
found that the concentration of Brazos River DOC was fairly independent of river discharge, while
the concentration of POC was generally dependent on the sediment load of the river, which is a
function of river discharge. Generally DOC was more indicative of organic pollution than POC.
Hill (1973) and Hill and Champ (in press) conducted a 25-hour diurnal study of 60 river
miles (8 stations-464 water samples) of the lower Patuxent River Estuary and found that the
variation of DOC was
insignificantly with relation to time except for one station down-river from an algal bloom.
The variation of DOC with relation to depth varies insignificantly at three stations and
significantly at three stations. DOC were significant at different ranges of salinity (1.40 ppt,
7.85 ppt, and 11.86 ppt) suggesting that DOC concentrations are not related to changes in
salinity. The variation of POC was always jointly significant for time and depth at any
particular station. The variation in POC was significant for time only at the bottom depth
(6.7 m ) but was always significant between the different stations at the 6.7 m depth. The
DOC concentrations were always higher than POC. The DOC/POC ratio for station means
was 1.7:1.0. Taking this data Ulanowicz and Flemer (1977) have estimated that on the
average over 20 metric ton atoms of organic carbon are produced each day by the study area
with 13.5 ton atoms of DOC and 6.7 ton atoms of POC. Hill and Champ (in press)
recommended that studies of this nature as was conducted on the Patuxent River (for 25
hours - 464 samples) need to be conducted on a seasonal basis to better understand the
distribution of DOC and POC in a tidal river estuary.
Sources (Point and Non Point)
The nation-wide significance of the contribution of combined and storm sewer
overflows caused by storm generated discharges (see Figure 1) was first identified in a U.S.
Public Health Service report (1964). Congress authorized funds under the FWPC Act of 1965
for research, development and demonstration of techniques for identifying and controlling
this source of pollution. Further authorization has been provided by the 1972 ammendments
to the act.
Pollution problems arising from combined and storm sewer overflows are widely
distribute through the United States, with the Northeast, Mid-west, and Far-west being the
principal problem areas. Field and Tafuri (1973) in a paper summarized the results of a
nation-wide survey conducted by the APWA. It was found that there were:
over 3,000,000 acres of combined sewer drainage area contained in more than 1,300
municipalities-with a population of 54 million served by some 55,000 mile of
combined sewers. Of the 641 jurisdictions surveyed, 493 reported some 14,200
combined sewer overflow points; 340 reported infiltration problems during wet-
weather; 96 indicated combined sewer overflows during dry weather.
In the District of Columbia, there are 12,418 sewered acres of which 31.9% are served
by combined sewers (NPDES Permit, 1974). On May 31, 1974, the D.C. Department of
Environmental Services was issued a National Pollutant Discharge Elimination System
Discharge Permit (NPDES Permit No. DC02119) to discharge serial numbers 001 through
060 to the Potomac River and its tributaries. The Structures account for 8,960 acres or 72.2
percent. of the total combined sewer acreage.
-2-
Weston (1970) found that combined sewer discharges represented a "significant portion" of the
total stormwater pollutional loads of the streams of the District of Columbia (BOD-56 percent,
suspended solids-41 percent, total phosphates-72 percent, and total nitrogen-64 percent). They
also reported that approximately one-half of the organic and more than 50 percent of the
nutrient loadings in combined sewer discharges originate from sanitary sewage and that the
average organic and nutrient concentrations of storm water (rainfall runoff) were found to be
approximately one-third of those in combined sewer discharges in the Washington, D.C. area.
Several researchers have found that street surface runoff is similar in many aspects to
sanitary sewage (Pravoshinsky and Gatillo, 1969; Sartor and Boyd, 1972; Vitale and Sprey,
1974). Periodic loads from storm events exert a demand which can be 40 to 200 times greater
than that of the normal dry weather effluent from the sewage treatment plant (Vitale and Sprey,
1974). Sartor and Boyd (1972) reported that the major constituent of street surface
contaminants was consistently found to be inorganic: similar to common sand and silt, which
is,probably blown-, washed or tracked in from surrounding land areas. Along with this material
is organic matter, a small fraction of the total on the basis of mass, Both fractions (organic and
inorganic) increase intensely in loading (lb/curb mile) with increasing time since the last
cleaning. Their data indicate, however, that the organic fraction tends to accumulate at a faster
rate than the inorganic fraction (Sartor and Boyd, 1972).
As preliminary data became available on the water quality of storm water (street-runoff,
combined and storm sewers) from other parts of the country, it was felt that organic carbon
concentrations in these sources in the Washington, D.C. Area must be monitored, to.determine
their contribution
to the Potomac River. Therefore this project was undertaken to investigate the distribution,
transport, cycling and sources of DOC and POC in the Potomac and Anacostia Rivers in the
Greater Washington D.C. area, because rivers with high organic carbon concentrations have
high BOD's and COD's which lower oxygen concentrations and finally cause oxygen
depletion and bring about high mortality to fish and other aquatic organisms.
The objectives of this study were to:
1. Investigate the distribution, transport and seasonal cycling of organic
carbon in the Greater Washington, D.C. area for the Potomac and
Anacostia Rivers.
2. Determine the relationships of organic carbon concentrations in the river
during periods of low and high flow and their relationship to flow.
3. Determine the influence that the tidal cycle has on organic carbon
concentrations with in the water column.
4. Determine the influence of municipal overflows on normal river organic
carbon concentrations and their rate of decomposition.
5. Evaluate the influence that street runoff, combined and storm sewer
overflows as point sources for organic carbon loadings to the River.
METHODS AND MATERIALS
STATION LOCATIONS
Water samples were collected and analyzed from the following array of stations: (1) Main
Channel stations on the, Potomac and Anacostia Rivers, (2) Special River Studies, (3)
Rock Creek, (4) Storm Sewers, (5) Combined Sewers, (6) National Park Runoff and (7)
Street Runoff.
Potomac River
Main Channel Stations
A weekly sampling program was conducted from March 15, 1975 to February 28, 1976
for eight Main Channel stations on the Potomac and Anacostia Rivers (see Figure 2). These
stations were selected with ease of location to fixed reference points (for example: bridges, piers
or buoys), The stations sampled were:
Station No. RM Station Location
1 101.1 Chain Bridge (River Mile 101)
2 98.1 Key Bridge
3 96.8 Memorial Bridge
4 95.4 14th Street Bridge
5 Capital Street Bridge (Anacostia River)
6 92 Blue Plains (above discharge pipe)
7 90.6 Wilson Bridge
8 87,5 Buoy 84 (River Mile 87.5) Adjacent to
Broad Creek
Water samples were collected by boat approximately 300 meters down river from all bridges.
Special River Studies
A series of* special studies were undertaken to determine the variation in the
concentrations of DOC and POC within the river system. A transect across the river was
conducted on June 24, 1975 at 100 foot intervals across the 1700 foot span of the river at
Memorial Bridge. A 24-hour diurnal (hourly sampling) was conducted on June 24 to June 25,
1975 at Memorial Bridge. A storm flood crest was sampled over September 26 to 28, 1975 at
Chain Bridge. To expand the sampling up river and down river, a one day collection effort was
conducted to sample from Shephardstown (RM 183) to the mouth (Point Lookout) on February
15, 1976. For this one day collection, samples above Key Bridge were collected from bridges, and
down river samples were taken by boat. Several other miscellaneous stations on the river were
sampled as the opportunity or interest arose.
VIRGINIA
BLUE PLAINS
Sewage Treatment Plant
POTOMAC Figure 2. Station locations
RIVER on the Potomac and
Anacostia Rivers.
Rock Creek
Beginning in November, 1975 for four months, four stations in Rock Creek
(within the Rock Creek National Park) were sampled: Rapids, Mill, Zoo and
Whitehurst Freeway. Samples were collected by rope-thrown bucket in the middle of
the stream from the bank just below the above mentioned reference points.
POINT SOURCES STUDY
Water samples were collected and analyzed for DOC and POC from selected
existing overflow structures in the Greater Washington area (see list below) to determine
the effect of overflows on natural organic carbon concentrations and the rate of their
decomposition. Since most of these overflows are not continuous but are intermittent,
they can only be sampled following periods of heavy rainfall. Samples were taken near
the mouth of the overflow structure to the river. The sampling rational was to establish
which overflow and monitor these during periods of heavy rainfall. Presented at the
beginning of the Appendix are descriptions for each sampling site. Appendix Figures 1-6
are specific maps to locate hard to find combined and storm sewer sampling sites (either
man hole openings or discharge pipes). All samples were collected by rope-thrown
bucket through the man hole opening or at the end of the discharge pipe. A complete list
of the NPDES Permit Overflows and their location is also given in Appendix Table 1.
Storm Sewer Overflows (with drainage acres)
Garfield Street - 86.75 acres
New Mexico Avenue - 48.65 acres
New York Avenue - 320 acres industrial (pipe #1)
- 393.4 acres residential and light commercial (pipe #2)
Combined Sewers (with drainage acres)
Northeast Boundary (DES #24) - 4,318 acres storm sewer
- 3,788 acres sanitary sewers
Easby Point (DES #34) - 518 acres sanitary sewers
- 555 acres storm sewers
Potomac River Punping Station (DES # 35)
- 26,143 acres sanitary sewers
- 35,408 acres storm sewers
30th and K Streets (DES # 38A)
- 582 acres sanitary and storm sewers
-7-
Combined Sewers Continued:
Potomac & Water Streets (DES 443) - 186 acres Sanitary and
Storm Sewers
Piney Branch (DES # 70, Rock Creek Park)
- 2,175 acres sanitary sewers
- 2,395 acres acres storm sewers
Street Runoff
Roundtree Subdivision (Seven Corners)
Loehmann's Plaza
Land Runoff
Washington Monument and Bicentennial Park Grounds
-8-
LABORATORY PROCEDURE
Dissolved and Particulate-Organic Carbon
Thirty ml aliquots of water sample were necessary for DOC and POC analysis. Water
samples collected in the field were frozen in acid cleaned (Dichromate, APHA-Standard Methods)
glass vials and stored in a deep freeze until filtered and sealed. A schematic diagram of the
organic carbon analysis is illustrated in Figure 3.
Frozen water samples prior to filtering were allowed to thaw at room temperature. Each
water sample was filtered through a precombusted Gelman Type A Glass Fiber Filter (0.3u) for
the partitioning of DOC and POC. The concentration (mg/1) of DOC and POC were determined
by modification of the method developed by Menzel and Vaccaro (1964), Fredericks and
Sackett (1970), and Brooks (1970). A step by step description (Champ, 1973) of this method is
listed below:
1. Thirty ml water samples were frozen in glass vials until time permitted filtering and sealing.
2. Ten ml glass ampules (Owens-Illinois) were prepared for use by being tapped upside down on a
clean surface (to remove any particles of foreign material) and the top of the neck of the
ampule wrapped with a piece of lightweight (one square) aluminum foil twisted to form a
cover for the ampule. Then ampules were pre-combusted at 5500C for four hours.
3. Gelman Type A (0.3micron) Glass Fiber Filters (25 mm diameter) were pre-combusted at
4000C for four hours. Filters were handled only with clean forceps.
4. Frozen water samples were allowed to thaw at room temperature prior to filtering and sealing
.
5. Four pre-combusted glass ampules were required for each water sample; giving replicate
analysis for DOC and POC. To each ampule 0.2 grams of potassium persulfate and 0.25
ml of 6% phosphoric acid solution were added prior to the addition of the sample to be
analysed.
6. Before filtering, water samples were briskly shaken and aliquots were removed by syringe.
7. Predetermined volume aliquots (river water samples: 5 mls; runoff and sanitary sewer samples:
0.25 mls to 3.0 mls) were taken into two syringes and filtered through millipore lock-on
syringe filter holders containing pre-combusted Gelman Glass Fiber Filters.
8. The two filters (each containing POC from the predetermined volume aliquot are vacuumed dry
with a water aspirator and inserted in ampules. Distilled water (5 mls) was then added to
each POC vial.
9. Predetermined volume aliquots (river water sample: 3 mls; runoff and sanitary sewer sample: 1
ml + 2 mls distilled water were then added by syringe to the two ampules for DOC
analysis.
10. Filled ampules were purged of inorganic carbon constituents for four to six minutes with
purified oxygen flowing at the rate of 60 mls/min., and then sealed in a special
sealing apparatus (designed by Oceanography International Corporation, College
Station, Texas) to prevent C02 contamination from the sealing flame.
11. Sealed ampules were heated at 1250C-40psi for four hours in an autoclave to oxidize
organic carbon to carbon dioxide. 12. The carbon dioxide content of each ampule
was then analyzed in a special ampule breaking apparatus (designed by Oceano-
graphy International Corp.) which permits the carbon dioxide content of each ampule
to be flushed through an infrared analyzer for analysis.
The carbon dioxide content of each ampule was determined by flushing the gas
content of the ampule with nitrogen into the gas stream of a nondispersive infrared analyzer
sensitized to carbon dioxide. The detector output of the analyzer is recorded as a peak on a
potentiometric strip chart recorder equipped with an integrator.
Standard carbon dioxide conversion graphs were made by plotting the integrated area
versus carbon for standardized sodium carbonate solutions. These standards were
determined by injecting a known volume of the sodium carbonate standard through a rubber
septum in a special vial containing phosphoric acid solution. The organic carbon
concentration of each ampule was determined by comparing the integrated area to the
standard carbon dioxide conversion graph and calculated by slope equation.
The deviation for duplicated DOC determinations on the same water sample were
generally 5% or lower, with POC usually 10% or lower. A reagent blank value was
determined with each set of water samples sealed. The DOC reagent value usually varies
from 0.003 mg C to 0.004 mg C.
-11-
RESULTS AND DISCUSSION
Distribution and Seasonal Cycling
Dissolved (DOC) and particulate (POC) organic carbon concentrations (mg/1) were
determined on a total of 783 water samples collected weekly from 7 main channel stations on
the Potomac River and 1 station on the Anacostia River from March 1975 to February 1976.
The data for each station are presented in Appendix Tables 2-6. Monthly means for DOC and
POC are presented in Tables 1 and 2. For the 41 dates sampled at 8 stations, the variation of
DOC and POC was insignificant by depth on each sampling date for all samples taken
(ANOVA-SPSS). The station at Blue Plains had the highest monthly mean. In retrospect,
selecting this site as a sampling station and sampling it near the outfall in the river was
unfortunately a poor decision. Because this station is not a sample of the discharge or of the
river, it is a sample of a point in the mixing zone and therefore, can not be used to access the
loading nor relative representation to other stations. The station in the Anacostia River had the
second highest monthly mean, reflecting possibly the overflows of combined and storm sewers
and/or the influence of the tidal transport of carbon from Blue Plains back into the Anacostia
since they are on the same side of the river. In the future more stations should be sampled to
determine the source of this high loading in the Anacostia River.
The monthly station means of DOC and POC (from Tables 1 and 2) are plotted in
Figures 4 and 5. The high readings reported for March 1975 are not analytical errors. We
have reanalyzed these samples. The high DOC and POC data for March correlate very well
with discharge. March had the highest monthly mean flow of 853.2 m3 /sec with a total
discharge of 26,446.8 m3/sec for the Water Year, 1975 (USGS, 1976). Both DOC and POC
illustrate a Summer rise in concentrations which correlate with low flows, warmer water
temperatures and increased productivity with both responding in a sigmoid shaped curve.
Increases in organic carbon concentrations in the Potomac River can be attributed to
two sources (1) autochthonous (from within - self production) ; primary productivity,
chemotrophic or heterotrophic processes and (2) allochtonous (from the outside); STP
discharges, overflows or runoff. The contribution can be estimated for the study area by
determining the percent change in organic carbon concentrations between seasons and
stations. The portion of the percent increase due to Blue Plains STP (350 MGD) discharge
can be estimated by determining percent change in mean organic carbon concentrations
between stations above and below the sewage treatment plant., For instance the organic
carbon concentrations in the study area during the winter are dervied from two allochthonous
sources (1) Blue Plains STP and (2) the resident river load being transported through the
study area. The autochthonous production at this time would be minimal due to low water
temperatures. The resident river organic carbon loading can be estimated from the data for
the winter months from those stations above Blue Plains STP with the Blue Plains
contribution being the difference between the stations above and below Blue Plains. Using
the winter data as the base, the percent change
-12-
between the winter and summer seasonal station means are also a rough estimate of net
productivity.
Table 3 presents the percent changes in seasonal means of DOC, POC and TOC
(DOC + POC). The Up-River stations averaged together are Chain, Key and Memorial
Bridges (the data from these stations are very similar, see Tables 1 and 2). Wilson
Bridge is below Blue Plains STP and Buoy 84 is below Wilson Bridge (see Figure 2).
Percent change has been calculated from the monthly means for the three areas (Up-
River, Wilson and Buoy 84) with Spring being April and May, Summer; June, July,
August and September, and Fall/Winter being October, November, December, January
and February
and determining the percent difference between each area. The Spring storm flood
occured in March and was not included in this analysis. For the Spring months it appears
that 19% of the percent change in DOC between Up-River and Wilson Bridge could be
attributed to discharge from Blue Plains STP (25%-6%) and that only 12 % (18%-6%)
could be attributed for the Summer Season (see Table 3). Suggesting that during the
Summer months 7% (25%18%) of the percent change was assimilated by the river
between the two areas. The POC and TOC data are harder to interpret because some
portion of the POC can settle out down-river.
The river mean percent change for the three areas for DOC for Spring to Summer
was +26y, while the mean percent change for Summer to Fall/Winter was -23X. POC for
Spring to Summer was +34%, while Summer to Fall/Winter was -39%. This seasonal flux
with a positive increase for the Spring to Summer and a negative increase (decrease) for the
Summer to Fall/Winter with the numbers (percent change) being very close (26 to 23 and 34
to 39) is very significant, almost text bookish (see Table 3). With the net increase and
decrease being very close, it suggests that the organic carbon loading from Blue Plains STP
did not exceed the assimilative capacity of the river on an annual basis. Further thinking is
needed in interpreting this data, because a river is a "one way trip" except for tidal
abberations and these considerations are being applied to different water masses passing a
point (or the assumption is that these water masses are not different) and that closed system
generalities are acceptable.
Carbon Production
To estimate the amount of carbon production in the study area, the lowest
monthly mean (May) was selected as the base. Only the three UpRiver Stations (Chain,
Key and Memorial Bridges) were utilized to reduce the contribution of organic carbon
from Blue Plains STP. Seasonal Means were calculated and compared (see
below).
The seasonal calculations for the Up-River Stations are: (mg/l)
Spring Summer Increase
DOC 2.68 3.79 1.11 or 29%
POC 1.82 3.26 1.44 or 44%
Summer Fall/Winter Decrease
DOC 3.79 2.94 0.85 or 22%
POC 3.26 1.78 1.48 or 45%
-17-
These results indicate that Summer Total Organic Carbon production can be estimated at
2.55 mg/l which is a 73% increase in river organic carbon concentrations.
Organic Carbon Transport Loadings
Organic carbon transport over Little Falls to the Potomac River Estuary was
estimated by multiplying the monthly mean discharge at Little Falls (453m3/sec) for the
study period (USGS, 1976, 1977) times the monthly mean concentration of DOC, POC and
TOC at Chain Bridge with the necessary conversion factors to calculate Metric Tons
transported/year.
The transport estimations are:
DOC - 5.4 x 104 MT/year
POC - 3.7 x 104 MT/year
TOC - 9.1 x 104 MT/year
In terms of carbon atoms only, the estimates are:
DOC - 4.5 x 103 MT atoms of carbon/year
POC = 3.1 x 103 MT atoms of carbon/year
TOC - 7.6 x 103 MT atoms of carbon/year
DOC/POC Ratio
A grand mean for DOC and POC was calculated utilizing all the
data available, yield the following results:
Grand Means ( ) - No. of Analyses
Station
DOC(mg/1) POC(mg/1) RATIO
Chain Bridge 3.54 2.55 1.4
(n=108) (n=108)
Key Bridge 3.56 2.48 1.4
(n=115) (n=115)
Memorial Bridge 3.55 3.55 1.4
(n=116) (n=115)
14th Street Bridge 3.98 2.56 1.5
(n=116) (n=115)
Blue Plains 6.03 4.46 1.5
(n=36) (n=37)
Wilson Bridge 4.37 2.71 1.6
(n=109) (n=110)
Buoy 84 4.00 2.56 1.6
(n=89) (n=89)
Anacostia River 5.05 2.87 1.8
(n=92) (n=92)
-19-
These results indicate that the mean DOC/POC Ratio for the Potomac River in the Greater
Washington Area is 1.4 to 1.6 with DOC being higher than POC. Brooks (1970) found
that generally DOC is more indicative of organic pollution than is POC. The results of this
study indicate that both DOC and POC increased in the vicinity of Blue Plains STP.
Special Studies
To expand the area of the Potomac River sampled, a one day collection effort was
conducted to sample from Shephardstown (RM 183.7) to the mouth (Point Lookout) on
February 15, 1976. The results are plotted in Figure 6 and presented in Appendix Table
10. Figure 6 has the 7 regular stations also plotted and illustrate the significant increase in
both DOC and POC down-stream from Blue Plains STP. The DOC/POC Ratio for just the
extra stations is 1.09, if the 7 regular stations are included the ratio is 1.31. Supporting
Brooks (1970) finding that DOC is generally higher in reaches of organic pollution.
A river storm crest was sampled before, during and after at Chain ,Bridge between
September 26 to 28, 1975. This sampling was during the maximum discharge recorded for
the water year 1975 (USGS, 1976). On September 27, the maximum discharge was 5,520
m3/sec. DOC and POC concentrations (mg/1) are presented in Figure 7 and Appendix
Table 11. The suspended sediment data is in Appendix Table 12. DOC was not effected by
increased discharge, which was also reported by Brooks (1970). POC and suspended
sediment correlate well together and with discharge. A second peak in POC was observed
which correlated with the maximum discharge recorded on September 27. Also the
DOC/POC Ratio was 0.6, further supporting the relationship of POC to discharge. Plotted
in Figure 8 is all of the DOC and POC data for Chain Bridge for the whole year. The data
demonstrates the small variation that occurs in DOC. The DOC/POC Ratio was 1.4
To determine tidal effects on DOC and POC concentrations, several special studies
were conducted. On June 24 and 25, 1975 a 25 hour diurnal study was conducted,
collecting water samples from surface, middle and bottom depths from Arlington
Memorial Bridge mid-channel in the Potomac River. The data are presented in Appendix
Table 13 and Figure 9. DOC and POC variations were insignificant with tidal cycle. The
DOC:POC ratio for the sample set was 1.07. To further evaluate tidal effects and
relationships, all of the data for the entire study was computer processed and a two way
ANOVA was conducted which found that the variation was also insignificant. On June 24
water samples were also collected at 100 ft intervals across the Potomac River at Memorial
Bridge at surface, middle and bottom depths to determine variation from bank to bank (see
Figure 10 and Appendix Table 14). The lateral variation was insignificant.
-20-
Rock Creek
Begining in November, 1975 for four months, four stations in Rock Creek (Rock Creek
National Park) were sampled. These stations were designated: Rapids, Mill, zoo and Whithurst. It
should be noted that Piney Branch (DES # 70) on Rock Creek was a sampling station for
combined sewer overflows.
The watershed of Rock Creek is largely vegetative areas (forests and fields) except for the
overflow at Piney Branch which has 4,570 . acres of storm and sanitary sewer runoff. The Piney
Branch overflow is held back by large weighted metal garage doors. For the four months
sampled, January had the highest concentrations of DOC and POC. Monthly means ranged from
2.69 mg/l to 6.13 mg/l for DOC. POC ranged from 1.20 mg/l to 4.65 mg/l demonstrating large
variations between sampling stations and dates (see Appendix Table 15). This is probable due to
very erratic flows and.a small stream retention volume. The mean of the monthly means was 3.88
mg/l and POC was 2.38 mg/l with -a ratio of 1.63. These organic carbon concentrations are
similar to those reported earlier for the Potomac River above Blue Plains.
POINT SOURCES
To be able to interpret organic carbon data (DOC and POC) from street runoff, combined
and storm sewer overflows the data must be compared to normal base line data for a receiving
waterway. Figure il presents mean DOC and POC concentrations for the following stations: (1)
six combined sewers, (2) New York Avenue storm sewers (residential and industrial combined),
(3) Garfield Street storm sewer, (4) New Mexico Avenue storm sewers, and (5) two sets of data
from the Potomac River (storm and annual). The significance of Figure 11 is that DOC and POC
concentrations from the combined and storm sewers varies significantly between sites and on
different sampling dates at the same site. It is also significant that all were above the background
concentration for the Potomac River (including the sample set for a storm crest of September 26-
28).
Storm Sewers/Street Runoff
Storm sewer samples from a residential area were generally lower in DOC and POC than
adjacent combined sewer samples. However it appears that a generality on this relationship does
not exist because other factors influence the concentrations in storm runoff. For example, in
Figure 11, comparison of residential street runoff concentrations over four dates sampled in
February indicate that in succeeding samples the elapsed time between rainfall is critical (see
means for 2-1 and 2-22). Comparison of shopping center runoff (Figure 12) to street runoff
illustrates the impact of local traffic volume and character on organic carbon concentrations. The
data for land runoff is only presented for comparison since the collection and samples from these
sites is very difficult due to slope and topography. It should be regarded as preliminary because
the collections were not made from a catch basin but from pools. Appendix Tables 16, 17, and 18
present street, storm, sewer and land runoff data.
-26-
Garfield Street storm sewer water samples were collected on July 9, 1975 at the
onset of flow (time 0, 15, 20, and 35 minutes). DOC was extremely high with a mean of
39.9 mg/1 and a plateau curve when graphed. POC concentrations ranged from 22.50 to
8.25 mg/l with a DOC:POC ratio of 2.9, one of the higher ratio's in the entire study (see
Figure 13). DOC and POC concentrations are plotted for the New Mexico Avenue storm
sewer overflow for July 9, 1975 in Figure 14. After 5 minutes of rainfall both appear as a
plateau curve on the graph with, the highest concentrations in the initial pulse (see Figure
14 and Appendix Table 19). The DOC:POC ratio was 2.8 with a mean DOC value of
24.4 mg/1. The following day , July 10, 65 minutes offlow was sampled. The DOC and
POC means were equal, 8.6 (see Figure 15). Apparently the flow from the previous day of
July 9 washed the storm sewer of the high concentrations of DOC and POC. The New
Mexico storm sewer was also sampled on February 22, 1977 over a 3 1/2 hour period
with the pulse of flow occurring around 1030 hr which correlated with the peak of POC.
For this sampling POC was higher than DOC (see Figure 16).
A third storm sewer overflow was also extensively sampled (New York Avenue - see
Appendix Table 20). For the February 13 sampling period, POC concentrations declined
sharply from the onset of rain and peaked at 25 minutes (see Figure 17). This station has a
separate overflow for industrial and residential discharges. However, both DOC and POC
concentrations were similar for the 90 minute period sampled on February 22, 1975 ( see
Figures 18 and 19). The overflows from the New York Avenue storm/sewer on March 5,
1975 were not similar for DOC or POC for either the industrial or the residential (see Figures
20 and 21).' In the industrial discharge DOC was higher while POC was higher in the
residential discharge illustrating tremendous variation in a storm sewer over three sampling
dates.
Combined sewers also exhibited tremendous variation. Figures 22 and 23 present data
for dry flow (without rainfall) for combined sewers on June 10, 1975 and February 27, 1976
(data in Appendix Table 21). For the June 10 samples the DOC concentrations were twice the
POC concentrations (ratio 1.9) and approximately 10 times higher than the river. On the
February sampling date, they were revised with the POC concentrations higher. Including
presampling rainfall (see Appendix Table 22) for June and February, we found that the
February sampling date had less rainfall prior to sampling, which could lead to a buildup of
POC in the combined sewers. Higher flow from a previous rainfall would increase the removal
of particulate material from the sewer line. Therefore, the next set of water samples would be
lower in POC as in Figure 21. Overflow DOC and POC for combined sewers is presented in
Appendix Table 23 for the Northeast Boundary site (DES-424) and the Potomac and Waters
site (DES-443). The May 8 sampling at Potomac and Waters had three days of previous
rainfall in five previous days. Therefore, it was not surprising that the DOC:POC ratio was 2.3
to 2.4 because POC had been washed from the sewer.- On the February 18, 1976 sampling,
very little previous rainfall had occurre4 and the DOC:POC ratio was .54 to .86 with a mean
ratio of 0.7.
-29-
It is apparent that the loading of DOC and POC in runoff is very complex. The
principal factors affecting the loading intensity at any given site include the following:
surrounding land use, the elapsed time since streets were last cleaned (either
intentionally or by rainfall), the degree of cleaning, local traffic volume and character
street surface type and condition, construction practices, public works practices, and
season of the year. These in turn affect the loading in storm and combined sewers and
their overflows.
In summary, generally DOC and POC concentrations in street runoff, storm and
combined sewers, and overflows were significantly higher (four to ten times) than
water samples from the Potomac River.
SUMMARY
This study collected and analyzed over 1000 water samples for dissolved and
particulate organic carbon. The study was designed to determine the background
organic carbon concentrations in the Upper Potomac River Estuary and major sources
in the Washington, D.C. area. In summary the concentration of organic carbon in
sources rarely did exceed one order of magnitude from background concentrations. It
appears that the major source of organic carbon, the Blue Plains Sewage Treatment
Plant, does have a significant effect on the organic carbon concentrations increasing
DOC and POC 20 to SO percent below the discharge. The DOC:POC ratio was higher
for the Greater Washington area than for upper reaches of the river indicating
municipal sewage loading.
The Appendix has been very carefully constructed to properly archive the data,
time of collection and location, stage of tidal cycle, rainfall, etc. in the event that
further analysis of the data can be made by other and future workers so that other
parameters analyzed by state and federal agencies can be compared and correlated.
Very rarely is duplicate analysis of every sample conducted as was done in this study.
-41-
CONCLUSIONS
1. Mean DOC and POC concentrations in the.Upper Potomac River Estuary reflect a
temporal (seasonal) and spacial (river mile) sigmoid shape curve.
2. Mean seasonal variation of DOC from above to below Blue Plains Sewage Treatment
Plant had a 26% increase from spring to summer and a 23% decrease from summer to
fall/winter.
3. Mean seasonal variation of POC from above to below Blue Plains Sewage Treatment
Plant had a 34% increase from spring to summer and a 39% decrease from summer to
fall/winter.
4. Mean seasonal organic carbon production estimates (percent change) using stations above
Blue Plains Sewage Treatment Plant derived values similar to those in the vicinity of Blue
Plains Sewage Treatment Plant.
5. Net total organic carbon production was estimated for stations to be 2.33 mg/l with
DOC = 0.85 mg/l and POC = 1.48 mg/1.
The metric tons of organic carbon transported annually by the Potomac River to the
Potomac River Estuary was estimated to be : DOC =
5.4 x 104 MT/yr, POC = 3.7 x 104 MT/yr, and TOC - 9.1 x 104 MT/yr.
7. The mean DOC:POC ratio for the Upper Potomac River Estuary was estimated to range
from 1.4 to 1.6.
8. In the River DOC does not correlate with discharge while POC does.
9. Variations in concentration of DOC and POC was insignificant with tidal activity or water
depth sampled in the river.
10. Lateral variation of DOC and POC (from bank to bank) was insignificant.
11. Storm sewer water samples from a residential area was generally lower in DOC and
POC than adjacent combined sewer samples.
12. Combined sewers exhibit tremendous variation in organic carbon concentrations.
13. POC concentrations in storm sewers varied in relationship with previous rainfall
occurance (flushing).
14. Generally, DOC and POC concentrations in street runoff, storm and combined sewer
overflows were significantly higher (four to ten times) than water samples from the Potomac
River.
-42-
RECOMMENDATIONS
1: When time and funding is available, conduct multivariate analyses with other
parameters of data collected by EPA or the state of Maryland for the Potomac River
during the same study period.
2. Design and secure funding for a future study to collect and analyze source water
samples for a greater array of chemical and physical parameters, in particular, dissolved
and particulate organic nitrogen and phosphate. The study should also include the
quantitative analysis of the discharge volume from the overflow structures in the
Washington, D.C. area. This will be the most costly portion of the study because the
automatic samplers operation of time is directly proportional to maintenance time. A
$3.50/hr graduate student is the most cost effective water sample collector, however, the
instrumentation and engineering costs to determine the volume of discharge in an
overflow will be very expensive.
3. Expand the number of stations in a given area and lengthen the reach of the river
studied to 80 or 100 miles.
4. Focus on assessing productivity rates (14C uptake studies) with organic carbon
production and determine retention and recycle rates.
5. Determine the impact that this high organic carbon loading has on other chemical
parameters, for example dissolved oxygen, and the biological response to such a load.
-43-
REFERENCES CITED
Biggs, R. B. and D. A. Flemer. 1972. The flux of particulate carbon in an estuary. Mar. Biol. 12:
11-17.
Brooks, J. M. 1970. The distribution of organic carbon in the Brazos River Basin. Masters
Thesis, Texas A&M University, College Station.
Champ, Michael A. 1973. Organic and inorganic carbon cycles in a pond ecosystem. Ph.D.
Dissertation, Texas A&M University, College Station.
Champ, Michael A. 1975. Nutrient loading in the nations estuaries. USEPA Report to Congress:
Estuarine Pollution Control and Assessment. Volume 1. pp 237-255.
Champ, Michael A., Dorothy L. Darden and Robert A. Noland. 1978. The nature of the Potomac
Estuary. Published in the Proceedings of the 1977 Fall Public Meeting: The Potomac
Estuary: Potential Water Supply. Interstate.Commission on the Potomac River Basin 78-
1, pp 10-14.
Champ, Michael A. 1978. Storm Runoff and Combined Sewers in Washington, D.C. Published in
the Proceedings of a Symposium: The Freshwater Potomac: Aquatic Communities and
Environmental Stresses. Interstate Commission on the Potomac River Basin. pp 151-154.
Duursma, E. K. 1961. Dissolved-organic carbon, nitrogen and phosphorus in the sea. Neth. J. Sea
Res. 1:1-147.
Duursma, E. K. 1963. The production of DOM in the sea as related to primary gross production
of organic matter. Neth. J. Sea Res. 2(1):85-94.
Field, Richard and Anthony N. Tafuri. 1973. Stormflow pollution control in the U.S. Combined
Sewer Overflow Seminar Papers. EPA-679/2-73007. pp 1-47.
Fredericks, A. D. 1968. Concentration of organic carbon in the Gulf of Mexico. Off. Naval Res.
Rept. 68-27T, 63 p.
Fredericks, A.D. and W. M. Sackett. 1970. Organic carbon in the Gulf of Mexico. J. of
Geophysical Res. 75:2199-2206.
Hill, J. M. 1973. Distribution and diurnal cycle of dissolved and particulate organic carbon in the
Patuxent River, Maryland. Masters Thesis, The American University, Washington, D.C.
Hill, J. M. and Michael A. Champ. (in press). Distribution of Dissolved and particulate organic
carbon over two tidal cycles in the Patuxent River Estuary, Maryland. File No. 1151 Estuaries.
27 p.
Loder, T. C. and D. W. Hood. 1972. Distribution of organic carbon in a glacial estuary in Alaska.
Limnol. and Oceanogr. 17(3):349-355.
-44-
Menzel, D. W. and R. F. Vaccaro. 1964. The measurement of dissolved organic and
particulate carbon in sea water. Limnol. Oceanogr. 9:138-142.
Menzel, D. W. 1964. The distribution of dissolved organic carbon in the Western Indian
Ocean. Deep Sea Res. 11:757-766.
Menzel, D. W. 1967. Particulate organic carbon in the deep sea. Deep Sea Res. 14(2):229-238.
Metcalf and Eddy, Inc., Engineers. 1971. Storm water problems and control in sanitary
sewers. EPA-11024EQG 03/71. 271 p.
Noland, Robert A. and Michael A. Champ. 1979. Application of the National Sanitation
Foundation Water Quality Index for the Potomac River (Kitzmiller to Possum Point)
plus selected tributaries (Monocacy River,; Anacostia River and Rock Creek) for April
to September 1977. Appendix to the Potomac River Basin Water Quality 1977.
Interstate Commission on the Potomac River Basin. 79-2
pp A-1 to 7.
Palmer, Richard N. 1975. Non-point pollution in the Potomac River Basin. The Interstate
Commission on the Potomac River Basin. Tech. Pub. 75-2. 71 p.
Parker, P. L. and J. A. Calder. 1968. Stable carbon isotopes variations in biological systems.
Symposium on Organic Materials in Natural Waters. University of Alaska, College.
Parsons, T. R. and J. D. H. Strickland. 1961. On the production of particulate organic oceanic
carbon by.hetertrophic processess in sea water. Deep Sea Res. 8:211-222
Pravoshinsky, N.S. and P.D. Gatillo. 1969. Calculation of water pollution by surface runoff.
International Association of Water Pollution Research. Minsk, USSR.
Sartor, James D. and Gail B. Boyd. 1972. Water pollution aspects of street surface
contaminants. EPA-R2-72-081. 237 p.
Sutcliffe, W. H.,E. R. Baylor and D. W. Menzel. 1963. The measurement of dissolved organic
and particulate carbon in sea water. Limnol. and Oceanogr. 9:139-142.
Ulanowicz, R. E. And D. A. Flemer. 1977. A synoptic view of a coastal plain estuary. In. J. C.
J. Nihoul, ed. Hydrodamics of Estuaries and Fjords. Elsevier, Amsterdam.
U. S. Comptroller General. 1973. Need to control discharges from sewers carrying both
sewage and storm runoff. U. S. General Accounting Office. B-166506. 47p.
U. S. Geological Survey. 1976. Water Resources Data for Maryland and Delaware Water Year
1975. USGS Water Data Report MD-75-1. 311 p.
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U. S. Geological Survey. 1977. Water Resources Data for Maryland and Delaware
Water Year 1976. USGS Water Data Report 76-1. 351 p.
Vitale, A. M. and P. M. Sprey. 1974. Total urban water pollution loads; The impact
of storm water. U.S. Council on Environmental Quality. NITS TB-231730.
183 p.
Weber, C. and D. R. Moore. 1967. Phytoplankton, seston and dissolved organic
carbon in the Little Miami River at Cincinnati, Ohio. Limnol. and Oceanogr.
12:311-318.
Weston, Roy F. Environmental Scientists and Engineers. 1970. Preliminary
engineering and applied research study, Washington, D.C. combined sewer
system (draft report). FWPCA. 182 p.
Wolman, Able and John C. Geyer. 1962. Report on sanitary sewers and waste water
disposal in the Washington Metroploitan Region. The Johns Hopkins
University. 143 p.
Wilson, R. F. 1963. Organic carbon levels in some aquatic ecosystems. Pub.
Institute of Mar. Sci. 9:64-76.
-46-
APPENDIX
-47-
POINT SOURCE STATION LOCATIONS
Overflow
EPA No. Street Location
Structure No.
East Capitol Street and
24 019
21st Street (extended), N.E.
Piney Branch Parkway, West
70 049
of 16th Street, N.W.
55 035 22nd Street, south of Q Street, N.W.
37 022 27th and K Streets, N.W.
38a* 024 30th and K Streets, N.W.
23rd Street, north of Constitution Avenue,
34 020
N.W.
Rock Creek and Potomac Parkway,
35 021 northeast of Theodore Roosevelt
Bridge, N.W.
43a 027 Potomac and Water Streets, N.W.
Bolling Air Force Base, about
2250 feet north of the south line
2 003
of the base and 800 feet east of
the Potomac River bank, S.W.
Bolling Air Force Base, about
2500 feet north of the south
4 003
line of the base and 1500 feet
east of the Potomac River bank, S.W.
16 011 Main Sewage Pumping Station, S.E.
-48-
POINT AND NON-POINT SOURCES SAMPLING
LOCATIONS STATION DESCRIPTIONS
STORM SEWERS
Garfield Street (See Figure 1)
The sampling site is located at Garfield and 43rd Streets, N.W., Washington, D.C. with
the displacement of the manhole cover at the intersection. Runoff characteristic of an entirely
residential area originates from such streets as Lowell, Kingle, Cathedral, and Hawthorne
Lane and travels via 45th and 44th Streets to where it becomes contained' on Garfield Street.
Samples are obtained at the four foot three inch pipe on Garfield Street before the runoff
enters the larger seven foot trunk storm sewer that follows Glover Archbold Parkway and
finally empties into the Potomac River. The frequency with which this sewer is used is
dependent upon anticipated rainfall and flows occur everytime significant precipitation
accumulates. The total drainage area of the sewer is 86.75 acres. An estimation of surface area
to grass would consist of 3/4 natural and 1/4 paved areas.
New Mexico Avenue (See Figure)
The New Mexico Avenue sampling site is near the intersection of Glover Archbold
Parkway and New Mexico Avenue in an embankment in the Park itself, in N.W.
Washington, D.C. The primary function of the storm sewer is to relieve New Mexico
Avenue, mostly a residential neighborhood consisting of Foxhall Terrace high rises with a
slight intervention of commercial businesses. This storm sewer commences at the junction of
Nebraska and New Mexico Avenues. It continues down New Mexico Avenue and ends as an
open flow into Glover Archbold Park at the point where Glover Archbold Parkway crosses
the western side of New Mexico Avenue. Then it becomes a
-49-
small stream running through the Park. The pipe narrows at the end which is a concrete bunker. The
frequency of utilization is as often as precipitation eventuates. There is a tendency towards erosion
during heavy rains. The total drainage area is, 48.65 acres. This sewer runs so close to the road that
an estimate of natural area would be 2/3 while 1/3 is paved surface.
New York Avenue
The water collection locale is situated in the field next to the outside turning lane of New York
Avenue approximately 800 yards east of Bladensburg Road in N.E. Washington, D.C., directly
across from the Holiday Inn and adjacent to the brick factory on New York Avenue. A branched
composite, the storm sewer drains separately half industrial S.W. D.C. and half residential N.W.
D.C. with the outflow of these two areas at New York Avenue still maintaining separate integral
samples. This allows collection of two types of distinct areas subjected to the same rainfall
conditions. Flows originate from the assemblages of Rhode Island and Mills Avenues and New
York Avenue and Brentwood Road, continue to New York Avenue where they flow concurrently to
the National Arboretum Creek that ultimately empties into the Anacostia River. The water drainage
flow of the area would correspond to the volume of rainfall and any differences would be due to the
functionality of the independent drainage segments. The total drainage is 713.4 acres, 320 of which
are highly industrial acres and 393.4 acres being residential and lightly commercial areas.
Approximately 3/4 of the highly industrial segment is unnatural, being concrete, while 1/4 of the
residential segment is unnatural.
-52-
COMBINED SEWERS
Northeast Boundary (DES X124)
This station, a manhole, is positioned close to a fireplug in front of the National Guard Armory
and on the side of R.F.K. Stadium opposite from the river. Light commercial, residential, and
small light industrial sectures all contribute sufficient amounts of flow as to make this a
combined sanitary and storm drainage sewer. During wet weather, there is spill over into the
Potomac River. There are 4,318 acres of storm drainage and 3,788 acres of sanitary drainage.
Easby Point (DES 1134. See Figure 3)
A bubbler, in a field by the Naval Department parking lot at 23rd Street and Constitution
Avenue, N.W. Washington, D.C. provides wet weather samples. This trunk sewer does
overflow frequently depending upon significant accumulation of precipitation, carrying
products of both sanitary and storm drainage of commercial downtown Washington, D.C.
Drainage is 518 acres sanitary and 555 acres of storm flows.
Potomac River Pumyina Station (DES 1135. See Figure 4)
This sampling site is located in a grass plot between a female and a male holly trees in
the parking lot of the Kennedy Center. An overflow bubbler is located approximately 30 feet
from this large, bolted down manhole. Residential, light commercial, and everything but heavy
commercial or industrial components contribute to the drainage of this sewer. Overflows occur
frequently here. The pumping station takes what it can handle and sends this to the Blue Plains
Treatment Facility. That which cannot be
-53-
handled empties into the Potomac River. The maximum input from all the Potomac River
Pumping Station tributary lines is 30 times the dry flow. It is able to pump five times the dry
flow. Overflows can occur at many points before it reaches the pumping station. From
beyond the Kennedy Center, the quantity is unmeasurable as over 36 overflow points occur
within the D.C. district before the sampling site. Drainage is 241,000 acres from Maryland
and Virginia. In Maryland, Rock Creek, Little Falls, and Captain John watersheds subscribe
to the flow. In Virginia, Scott, Pirret, and Date runs provide input. Total storm drainage is
35,408 acres. Total sanitary drainage is 26,143 acres.
30th and K Streets (DES 4138A. See Figure 5)
Sampling of this location is at the last access point before the Potomac River, a manhole,
at 30th and K Streets, N.W., Washington, D.C. In addition, affixed to this sewer is a bubbler
recorder which keeps year round data of any overflow. Designated overflow is that material
which the plumbing and piping can no longer handle and goes out into the Potomac River. A
Model # 24 Automatic sampler also collects water overflow. The D.C. Sanitation
Department installed these two devices during the summer of 1975 of which they have only
been operational for one month during the summer. Runoff starts at Rock Creek Drive just off
of Massachusetts Avenue. This sewer combines the handling of residential and light
commercial sewage with storm flows. An odd sewer, partitioned in the center, the left hand side
(looking up from the river, upflow) is a combined sanitary and storm sewer while the right hand
side (looking up from the river, upflow) is sanitary only. There is a merging of combined flow
in the pipe. The total
-56-
drained is a composite of these sites.
drainage acres and acres both storm and sanitary
241 Norman Stone Stream 211
63 Mass. Ave. & White Haven 61
152 Montrose 115
12 Q Street 8
110 0 & 31st Streets 105
15 Olive & 29th Streets 14
40 M & 27th Streets 35
13 28th St. & Wisconsin Ave. 13
75 Local next to piping 20
721 Total 582
This is the total minus the unsewered areas, cemeteries and parks, within these boundaries.
Potomac and Water Streets (DES 443. See Figure 6)
The access point for this section of Georgetown can be found at Potomac and Water
Streets, N.W., Washington, D.C. The sewer is employed for both sanitary and storm drainage.
Water is dispersed from the residential section west of Wisconsin Avenue, East of
Georgetown University which is a light commercial and residential area, and R Street to
where it drains into the Potomac River. The sampling site is dependent upon weather
conditions. During dry weather, samples are obtained from a manhole on Potomac Street, 20
feet up from the intersection of Potomac and Water Streets. Overflow is obtainable through
the automatic sampler from an overflow pipe approximately 60 feet from the river between
the manhole and the river outlet itself. Overflows occur quite frequently due to construction
of the outflow dam at this site. The sewer opens into the Potomac River below Key Bridge
but the tide is always backed up into it. The sewer drainage is 186 acres.
-58-
Rock Creek Park (DES #70.)
This sewer outlet is located on the northern side of Piney Branch Parkway, 1/2 mile
up from the intersection of the Parkway and Beach Drive. The area is primarily residential
with the addition of light commercial. There are 2,395 acres of storm drainage and 2,175
acres of sanitary drainage that come from the same area.
National Park Runoff
Samples were collected from The Washington Monument grounds and The
Bicentennial Park from grassland vegetation on two sampling dates.
Street Runoff
Street runoff was collected from storm sewers (described previously), shopping centers
and residential areas. Due to the irregularity of rainfall in the Washington, D. C. area, and the
significant portion of rainfall that occurs after 10:00 p.m., the Principal Investigator sampled
street rainfall in selected areas near his home in Roundtree subdivision south of Route 50 and
Graham Road (in Virginia near Seven Corners). Shopping center runoff samples were
collected from Loehmanns Plaza in the same area.
-60-
Table l. Listing and location of current and proposed overflow structures located
on the Potomac River Watershed in the Greater Washington, D.C. Area, with the
discharge receiving waters and frequency of occurence. Source: The District of
Columbia's National Pollutant Discharge Permit (No. D00021199) from the U.S.E.P.A.,
Region III, for the period of June 30, 1974 to June 30, 1979.
Discharge Overflow Structure Location Discharge Frequency
Serial (or discharge) Receiving Occurrence
No. Water
Existing D.C. Water Pollution
00l Control Plant Outfall Potomac River
Continuous
002 New D.C. Water Pollution Potomac River
(Proposed) Control Plant Outfall
Wet & Dry
003 Bolling., Air Force Lace Potomac River
Weather
Poplar Point Sewage Pumping Anacostia River,
004 Wet Weather
Station S.E. East Side
Chicano Street and Railroad. Anacostia River,
005 Wet Weather
Avenue, S.E. East Side
Good Hope Road, ties: of Anacostia River,
006 Wet Weather
Nichols Avenue, S.I. East Side
13th Street and Ridge Place, Anacostia River,
007 Wet Weather
S.E. East Side
Anacostia Avenue, West of Anacostia River, Emergency
008
Blaine Street, \.E. East Side By Fass
2nd Street 300 _feet north Anacostia River,
009 Wet Weather
of N Place, S. E. West Side
O Street Sewage Pumping Anacostia River,
010 Wet Weather
Station, S.E. West Side
Main Sewage Pumping Station Anacostia River,
011 Wet Weather
West Side
North of Main Sewage Pumping Anacostia River, Wet Weather
012
Station, S.E. West Side
4th & N Streets, S.E., Both Anacostia River,
013 Wet Weather
Extended West Side
Anacostia River,
014 6th & M Streets, S.E. Wet Weather
West Side
Anacostia River,
015 9th & M Streets, S.E. Wet Weather
West Side
-61-
Discharge Overflow Structure Location Discharge Frequency
Serial No. (or discharge) Receiving Occurrence
Water
Anacostia River,
016 12th and M Streets, S.E. Wet Weather
West Side
Anacostia River,
017 14th & M Streets, S.E. Wet Weather
West Side
Barney Circle & Pennsylvania Anacostia River,
018 Wet Weather
Avenue, S.E. West Side
N.E. Boundary Trunk vic. of Anacostia River,
019 Wet Weather
25th & E Sts. S.E. extended West Side
23rd Street, North of Consti- Potomac River,
020 Wet Weather
tution Avenue, N.W. East Side
Northeast of Roosevelt Bridge, Potomac River,
021 Wet Weather
N.W. East Side
Potomac River,
022 27th & I Struts, N.W. Wet Weather
East Side
Potomac River,
023 29th & K Streets, N.W. Wet Weather
East Side
Potomac River,
024 30th & K Streets, N.W. Wet Weather
East Side
Potomac River,
025 31st & K Streets, N.W. Wet Weather,
East! Side
Wisconsin Avenue and K' Potomac River,
026 Wet Weather
Streets, N.W. East Side
Potomac River,
027 Water Street West of
East Side Wet Weather
Potomac Street, N.W.
.
028 Potomac River,
36th & M Streets, N.W. Wet Weather
East Side
029 Canal Road 1000 ft. East of Potomac River,
Wet Weather
Foxhall Road, N.W. East Side
030 Potomac River,
Foxhall & Canal Roads, N.W. Wet Weather
East Side
-62-
Discharge Overflow Structure Location Discharge Frequency
Serial (or discharge) Receiving Occurrence
No. Water
Pennsylvania Ave., East Side Rock Creek, Wet Weather
031
of Rock Creek, N.W. East Side Rare
Rock Creek, Wet Weather
032 26th & M Streets, N.W.
East Side Rare
N Street Extended West of Rock Creek, Wet Weather
033
25th Street, :1.W. East Side Rare
Rock Creek, Wet Weather
034 23rd and 0 Streets, N.W.
East Side Rare
22nd Street South of Q Street, Rock Creek, Wet Weather
035
N.W. East Side Rare
23rd Street South of Q Street, Roc}: Creek, Wet Weather
036
N.W. East Side Rare
N.W. of Belmont Road and Rock Rock Creek, Wet Weather
037
Creek G Potomac Parkway East Side Rare
North of Belmont Road, East Rock Creek, Wet Weather
038
of Kalorama Circle, N.W. East Side Rare
Connecticut Avenue, East of Rock Creek, Wet Weather
039
Rock Creek, N.W. East Side Rare
Biltmore Street, Extended, Rock Creek, Wet Weather
040
East of Rock Creek, N.W. East Side Rare
Ontario, Extended, and Rock Rock Creek, Wet Weather
041
Creek Park-way East Side Rare
Harvard Street S Rock Creek Rock Creek, Wet Weather
042
Parkway, N.W. East Side Rare
Adams Mill Road, South of Rock Creek, Wet Weather
043
Irving Street, N.W. East Side Rare
Kenyon Street and Adams Mill Rock Creek, Wet Weather
044
Road, N.W. East Side Rare
Adams Mill Road and Lamont Rock Creek, Wet Weather
045
Street, N.W. East Side Rare
Discharge Discharge
Overflow Structure Location Frequency
Serial Receiving
(or discharge) Occurrence
No. Water
Park Road, South of. Piney Rock Creek, Wet Weather
046
Branch Parkway, N.W. East Side Rare
Ingleside Terrace, Extended, Rock Creek, Wet Weather
047
and Piney Branch Parkway Base Side Rare
Mt. Pleasant Street, Extended Rock Creek, Wet Weather
048
and Piney Branch Parkway East Side Rare
Piney Branch Parkway, West of Rock Creek, Wet .,leather
049
16th Street, East Side Rare
28th Street, West of Rock Rock Creek, Wet Weather
050
Creek Parkway, N.W. West Side Rare
Olive Street, Extended, and Rock Creek, Wet Weather
051
Rock Creek Parkway, N.W. West Side Rare
O Street, Extended, and Rack Rock Creek, Wet Weather
052
Creek Partuay, N.W. West Side Rare
O Street, West of Rock Creek Rock Creek, Wet Weather
053
N.W. West Side Rare
West Side of Rock Creek, 300 Rock Creek, Wet Weather
054
ft. South of Mass. A•re., N.W. West Side Rare
Massachusetts ?venue and Rock Creek, Wet Weather
055
Whitehaven Street, N.W. West Side Rare
Normanstone Drive, Extended, Rock Creek, Wet Weather
056
West of Rock: Creek, 'T.W. West Side Pare
28th Street, Extended, West Rock Creek, Wet Weather
057
of Rock; Creek, N.W. West Side Rare
Connecticut Avenue and Rock Rock Creek, Wet Weather
058
Creek Parkway, N.W. West Side Rare
16th. 6 Rittenhouse Streets, Rock Creek, Wet Weather
059
N.W. West-Side Rare
Little Falls Emergency
060 Little Falls Branch
Branch By Pass
Table 2. Dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg C/liter) for Chain Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Mar 15 6.58 1.56 6.83 1.80 5.42 1.34 6.28 1.57
29 11.19 2.79 12.32 2.83 12.32 2.07 11.95 2.57
Apr 11 1.25 0.74 2.47 0.75 1.13 4.30 1.62 1.93
19 2.22 1.77 1.94 0.49 3.09 2.31 2.42 1.52
26 3.29 4.08 3.17 1.47 3.02 4.35 3.16 3.30
May 2 4.51 1.33 2.89 1.01 3.49 1.76 3.63 1.37,
8 3.89 2.15 2.72 1.71 2.76 2.66 3.13 2.18
17 2.10 1.49 2.60 1.58 1.74 1.44 2.15 1.51
22 2.19 1.43 2.32 1.66 2.93 1.49 2.48 1.53
31 3.62 2.66 3.37 2.90 2,08 1.87 3.03 2.48
Jun 7 4.49 3.06 3.97 3.64 3.95 3.22 4.14 3.31
13 3.81 2.58 3.22 2.93 3.12 2.92 3.39 2.81
20 4.53 4.53 3.03 3.22 3.37 3.18 3.65 3.65
26 3.23 2.68 3.68 6.64 3.53 6.54 3.48 5.29
Jul 4 4.16 2.17 3.44 2.17 4.64 2.58 4.08 2.31
11 4.63 2.82 4.74 3.16 4.03 2.61 4.47 2.87
18 3.28 1.76 2.70 1.65 2.96 1.47 2.98 1.63
24 4.18 1.93 3.58 1.90 3.27 1.65 3.68 1.83
31 4.62 7.19 5.16 6.44 4.63 3.78 4.81 5.81
Aug 8 3.77 3.49 3.45 3.59 3.43 3.21 3.55 3.43
16 3.18 3.64 4.39 3.63 3.82 3.69 3.80 3.66
21 3.65 2.73 3.25 2.30 3.62 2.76 3.51 2.60
28 4.53 3.09 4.51 3.16 4.01 2.83 4.35 3.03
Sep 26 See Table
Oct 3 2.98 1.60 2.28 1.60 1.66 1.61 2.31 1.61
9 2.58 2.19 1.71 0.59 2.74 1.36 2.35 1.38
24 3.47 1.56 2.61 2.29 2.99 1.73 3.03 1.86
31 2.97 0.76 2.51 0.75 2.69 0.78 2.73 0.77
Nov 7 4.49 1.19 2.53 1.05 2.36 0.69 3.13 0.98
20 3.02 0.51 3.34 0.98 2.47 1.21 2.95 0.90
26 2.47 1.13 2.15 1.15 2.20 1.40 2.28 1.23
Dec 5 2.38 0.79 2.63 0.87 '2.81 1.54 2.61 1.07
12 3.27 1.34 2.94 1.50 3.06 1.83 3.09 1.56
Table 2 Ctn-Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Chain Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Jan 24 2.79 1.14 --- ---- -- --- 2.79 1.14
31 5.28 3.44 -- ---- ---- ---- 5.28 3.44
Feb 7 3.45 1.74 -- --- ---- -- 3.45 1.74
15 1.87 1.77 2.12 1.44 1.76 1.46 1.91 1.56
20 2.14 2.13 2.67 1.94 2.03 2.13 2.28 2.07
28 3.50 2.72 2.69 2.55 4.56 3.44 3.59 2.91
Grand Means: DOC = 3.54 (n=108)
POC = 2.55 (n=108)
Ratio 1.39
Table 3. Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Key Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Mar 1 5.99 1.76 7.59 2.94 6.82 3.44 6.80 2.72
15 7.22 1.23 6.32 1.54 6.42 0.67 6.66 1.15
21 3.72 8.73 ---- --- --- ---- 3.72 8.73
29 10.64 4.18 12.46 3.34 11.47 1.74 11.53 3'.09
Apr 11 1.63 1.74 1.71 1.28 1.34 1.73 1.56 1.59
19 1.65 1.85 2.22 1.36 2.12 0.98 2.00 1.40
26 6.18 3.07 2.83 2.40 3.15 2.20 4.06 2.56
May 2 2.96 1.96 3.03 1.47 3.36 2.56 3.12 2.00
8 2.72 3.23 3.20 2.46 3.11 1.11 3.01 2.27
17 1.99 1.41 2.22 1.54 2.76 2.60 2.33 1.85
22 2.36 1.48 2.62 1.49 2.97 1.99 2.65 1.66
31 2.63 1.70 1.90 1.24 1.71 1.57 2.08 1.51
Jun 7 4.08 1.80 4.06 2.57 3.92 2.40 4.02 2.26
13 2.83 2.71 4.15 2.93 2.71 2.58 3.23 2.74
20 5.60 3.57 3.11 2.43 4.27 2.58 4.33 2.86
26 4.29 7.64 2.84 3.01 3.56 7.74 3.57 6.13
Jul 4 3.58 2.52 4.06 1.48 5.35 3.15 4.33 2.39
11 3.83 2.72 4.09 2.48 3.32 2.50 3.75 2.57
18 3.51 1.51 2.83 1.30 1.67 2.23 2.67 1.68
24 3.27 1.42 2.75 1.85 2.10 2.29 2.71 1.86
31 7.29 8.14 4.82 8.02 5.92 11.27 6.01 9.15
Aug 8 3.94 3.52 4.05 3.41 3.61 4.69 3.87 3.88
16 3.12 2.80 3.73 3.45 3.42 3.33 3.43 3.20
21 3.84 2.22 4.54 1.91 3.69 2.01 4.03 2.05
28 3.87 2.86 3.52 2.17 4.69 5.56 4.03 3.53
Sep 13 4.00 5.64 2.52 4.36 3.21 2.69 3.25 4.23
Oct 3 2.71 1.98 4.22 2.23 4.79 3.67 3.91 2.63
9 2.12 1.23 2.56 1.56 2.48 0.76 2.39 1.19
24 2.76 2.26 2.93 1.52 2.65 1.84 2.78 1.88
31 2.35 0.92 2.58 0.70 2.56 0.48 2.50 0.70
Nov 7 1.36 1.12 1.18 0.71 2.12 0.76 1.56 0.87
20 2.39 1.15 4.18 0.81 2.98 1.05 3.19 1.01
26 2.56 1.42 2.69 1.67 2.06 1.48 2.44 1.53
Dec 5 2.56 1.59 5.13 1.70 2.75 1.97 3.48 1.76
12 3.39 1.47 2.86 1.75 2.96 2.23 3.07 1.82
-67-
Table 3Ctn- Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Key Bridge station for indicated dates and depths
Date Surface :diddle Bottom X X
(1975- (DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Jan 24 2.11 1.11 ---- --- ---- -- 2.11 1.11
31 3.57 3.71 ---- ---- ---- ---- 3.57 3.71
Feb 7 3.47 1.29 ----- ---- ----- --- 3.47 1.29
15 1.67 1.42 2.38 1.31 1.30 1.05 1.79 1.26
20 3.20 1.57 2.29 2.25 1.87 2.12 2.46 1.98
28 2.73 3.79 3.49 2.13 4.40 4.04 3.54 3.32
Grand Means: DOC = 3.56 (n=115)
POC = 2.48 (n=115)
Ratio 1.44
-68-
Table 4. Dissolved (DOC) and particulate (POC) organic carbon concentrations (mg
C/liter) for Memorial Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Mar 1 4.62 1.58 6.60 2.32 6.76 3.62 6.00 2.51
15 6.42 1.39 5.98 0.18 4.92 1.50 5.78 1.03
21 8.56 10.54 8.56 12.60 6.79 11.11 7.97 11.42
29 11.14 2.30 9.57 3.07 9.14 3.11 9.95 2.83
Apr 11 5.20 3.26 2.88 1.83 2.45 1.22 3.51 2.11
19 2.30 1.21 2.61 1.74 2.85 2.46 2.59 1.81
26 2.70 3.11 2.95 4.78 2.50 4.61 2.72 4.17
May 2 2.47 1.71 2.29 1.63 2.87 1.92 2.55 1.76
8 3.11 1.62 4.84 2.23 2.98 1.84 3.65 1.90
17 1.60 1.55 2.40 1.68 2.58 1.62 2.20 1.62
22 2.40 1.92 3.26 1.75 2.20 1.26 2.62 1.65
31 1.40 1.65 1.62 1.41 1.44 2.98 1.49 2.02
Jun 7 3.68 1.59 3.06 2.11 3.04 1.75 3.26 1.82
13 3.19 2.74 2.91 2.60 3.22 2.18 3.11 2.51
20 3.79 2.70 2.85 2.72 2.82 2.74 3.16 2.72
24 See Table
26 3.23 2.78 3.73 7.04 3.25 2.31 3.41 4.05
Jul 4 4.77 2.03 4.43 2.27 4.29 2.05 4.50 2.12
11 3.76 2.68 3.87 2.48 3.94 2.61 3.86 2.59
18 3.15 1.24 2.60 1.47 3.02 1.59 2.93 1.44
24 3.21 ---- 3.53 1.94 3.52 1.89 3.42 1.92
31 4.42 7.74 3.75 8.49 4.34 8.92 4.17 8.39
Aug 8 3.45 3.77 3.26 3.61 3.52 3.09 3.41 3.49
16 3.58 3.38 3.52 3.18 5.00 3.87 4.04 3.48
21 7.15 5.72 3.89 2.24 4.32 2.68 5.12 3.55
28 3.95 3.39 4.71 2.41 3.68 2.82 4.12 2.88
Sep 13 2.77 2.10 3.08 2.73 2.61 ---- 2.82 2.42
Oct 3 2.73 1.27 1.39 0.96 1.44 1.15 1.86 1.13
9 2.45 1.46 2.03 1.16 2.58 2.12 2.36 1.58
24 1.72 1.95 2.71 1.71 3.17 2.33 2.54 2.00
31 2.60 0.76 3.27 1.31 2.67 0.83 2.85 0.97
Nov 7 1.59 0.69 1.02 1.06 3.51 1.41 2.04 1.06
20 3.46 1.85 3.32 1.37 2.90 0.89 3.23 1.37
26 2.96 1.71 2.51 1.56 2.49 1.53 2.66 1.60
Dec 5 2.89 1.37 2.69 1.07 1.87 2.06 2.49 1.50
12 3.49 1.33 3.04 1.25 3.06 1.01 3.20 1.20
-69-
Table 4 Ctn- Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Memorial Bridge station for indicated dates and
depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Jan 24 1.87 2.65 1.87 2.65
31 5.80 4.31 --- ---- --- ---- 5.80 4.31
Feb 7 3.50 1.63 --- --- ---- --- 3.50 1.63
15 --- 1.69 2.12 1.57 1.99 1.48 2.06 1.58
20 1.94 2.01 2.76 1.88 2.78 2.36 2.50 2.09
28 4.26 2.83 4.64 2.84 3.28 2.38 4.06 2.69
Grand Means: DOC = 3.55 (n=116)
POC = 2.56 (n=115)
Ratio 1.39
-70-
Table 5. Dissolved (DOC) and particulate (POC) organic carbon concentrations (mg
C/liter) for 14th Street Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Mar 1 6.61 1.19 5.06 3.23 5.27 1.98 5.65 2.14
15 7.72 1.61 8.18 2.54 4.61 3.02 6.84 2.39
21 5.54 15.04 6.82 ---- 6.69 19.84 6.35 17.44
29 12.60 3.50 11.19 3.40 12.84 4.10 12.21 3.67
Apr 11 6.10 1.21 3.65 1.02 3.01 1.28 4.26 1.17
19 2.70 0.76 2.70 1.86 2.36 1.67 2.59 1.43
26 3.41 2.24 2.72 2.45 2.86 3.57 3.00 2.76
May 2 2.56 1.68 2.52 1.44 2.83 1.76 2.64 1.63
8 8.00 4.18 4.52 3.54 3.91 3.06 5.48 3.60
17 2.47 1.55 2.37 3.32 2.16 1.42 2.34 2.10
22 1.22 1.22 2.06 1.50 2.04 1.35 1.78 1.36
31 3.85 3.98 3.88 2.93 2.21 4.46 3.32 3.79
Jun 7 5.54 3.04 3.97 1.64 3.33 1.67 4.28 2.12
13 3.02 2.41 2.81 2.52 2.76 4.24 2.87 3.06
20 3.87 2.99 3.22 3.47 2.82 2.58 3.31 3.02
26 3.56 2.33 3.56 3.33 4.62 2.98 3.92 2.88
Jul 4 6.95 2.93 5.59 2.07 4.53 2.60 5.69 2.54
11 4.38 2.55 4.16 2.55 3.80 2.20 4.12 2.44
18 3.15 2.46 4.70 1.68 3.86 2.22 3.91 2.12
24 3.82 2.11 3.58 2.16 3.98 1.95 3.80 2.08
31 5.13 4.96 4.97 10.07 4.68 9.32 4.93 8.12
Aug 8 4.20 4.56 3.64 3.11 3.41 2.97 3.75 3.55
16 6.02 2.90 11.57 3.66 3.79 2.87 7.13 3.15
21 6.96 2.80 5.03 4.77 4.19 2.62 5.40 3.40
28 4.47 2.26 2.80 3.02 3.00 2.08 3.43 2.46
Sep 13 4.16 2.13 3.82 2.13 3.14 2.02 3.71 2.10
Oct 3 1.72 1.35 1.92 1.01 1.70 1.14 1.78 1.17
9 2.74 1.04 1.91 0.77 1.56 0.56 2.07 0.79
24 3.65 1.00 2.79 2.05 3.39 1.80 3.28 1.62
31 2.32 1.04 2.48 0.67 2.26 0.89 2.36 0.87
Nov 7 8.49 1.97 3.30 1.00 1.36 1.53 4.39 1.50
20 2.19 1.45 2.72 0.89 2.40 1.45 2.44 1.27
26 2.38 1.23 2.94 1.75 2.76 1.69 2.70 1.56
Dec 5 2.36 1.15 2.57 0.99 2.55 1.82 2.50 1.32
12 ---- --- 2.89 1.13 2.21 1.01 2.55 1.07
Table 5.Ctn- Dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg C/liter) for 14th Street Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975- (POC) (DOC) (POC)
(DOC) (POC) (DOC) (POC) (DOC)
1976)
Jan 24 2.21 1.22 ___ 2.21 1.22
31 6.81 4.30 ---- ---- ---- 6.81 4.30
Feb 7 3.15 1.99 ----- ---- ---- ---- 3.15 1.99
15 2.40 2.19 2.69 2.31 2.58 1.82 2.83 3.16
20 2.58 2.38 2.47 1.74 3.89 2.11 2.98 2.08
28 4.09 3.95 4.84 2.44 4.17 3.21 4.37 3.20
Grand Means: DOC = 3.98 (n=116)
POC = 2.64 (n=115)
Ratio 1.51
-72-
Table 6. Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Anacostia River station for indicated dates and depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Apr 11 6.12 4.66 3.49 1.11 ---- ---- 4.81 2.89
26 5.69 4.30 4.39 3.70 5.05 2.76 5.05 3.59
May 2 4.11 1.65 4.25 2.42 3.85 2.42 4.07 2.17
8 5.37 2.65 5.68 2.80 5.37 2.66 5.48 2.71
17 4.82 2.88 3.54 1.86 3.71 1.89 4.03 2:21
22 4.49 1.74 4.58 2.38 6.20 2.36 5.09 2.16
31 4.42 2.67 3.65 2.40 4.37 2.97 4.15 2.68
Jun 7 5.27 2.19 4.33 1.66 5.05 2.14 4.89 2.00
13 4.46 1.66 5.06 5.38 4.86 2.74 4.80 3.26
20 8.48 ‘4.12 4.55 2.54 5.58 3.03 6.21 3.23
26 4.88 3.45 4.72 3.08 5.21 3.23 4.94 3.26
Jul 4 6.28 2.68 6.44 3.33 10.97 3.25 7.90 3.09
11 6.95 4.07 6.19 2.96 6.15 3.21 6.43 3.42
18 4.59 2.82 5.27 2.28 4.98 1.98 4.95 2.36
24 6.54 3.26 6.14 2.34 5.73 3.33 6.14 2.98
31 5.09 4.06 5.91 2.70 6.19 3.26 5.73 3.34
Aug 8 6.65 3.90 6.05 3.59 7.22 3.84 6.64 3.78
16 5.10 2.52 4.47 2.17 7.83 2.67 5.80 2.46
21 7.12 2.67 5.63 2.11 2.89 2.48 5.22 2.42
28 5.42 3.62 5.10 6.25 5.00 4.26 5.18 4.71
Oct 3 4.88 2.86 4.13 2.59 3.43 3.13 4.15 2.86
9 3.73 2.09 3.73 2.38 3.65 3.05 3.71 2.51
24 4.38 2.17 4.84 2.13 4.26 2.39 4.50 2.23
31 4.29 1.60 5.32 1.85 4.25 2.61 4.62 2.02
Nov 7 2.72 1.90 2.83 1.95 2.41 2.93 2.66 2.26
20 7.21 2.51 5.47 2.71 5.54 4.16 6.08 3.13
Dec 5 4.37 1.82 4..37 2.20 4.41 2.16 4.39 2.06
12 4.34 1.66 3.89 1.69 4.07 2.18 4.10 1.85
Jan 24 2.65 1.28 ---- ---- ---- ---- 2.65 1.28
31 9.06 4.10 ---- ---- ---- ---- 9.06 4.10
Feb 7 5.36 2.50 ---- ---- ---- ---- 5.36 2.50
20 1.54 3.83 4.71 3.58 4.00 3.31 3.42 3.58
28 6.42 5.19 6.21 3.98 4.77 3.65 5.80 4.28
Grand Means: DOC = 5.05 (n=92) POC = 2.87 (n=92) Ratio 1.76
-73-
Table 7. Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Blue Plains station for indicated dates and depths
Date Surface Mi Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Mar 1 11.36 2.63 ---- ---- 6.30 2.07 8.83 2.35
15 10.49 2.26 ---- ---- 11.73 6.06 11.11 4.16
21 3.80 7.98 24.80 12.88 7.05 11.23 11.89 10.70
29 20.15 4.76 ---- ---- 20.31 7.87 20.23 6.32
Apr 11 8.09 8.74 2.59 0.97 5.34 4.86
19 3.68 4.76 ---- ----- 3.68 4.76
26 4.92 4.64 3.82 3.31 4.37 3.98
May 2 5.18 3.26 ---- ---- 3.27 1.52 4.23 2.39
8 3.60 1.56 ---- ---- 3.78 3.37 3.69 2.47
17 2.94 1.61 2.49 1.75 1.74 1.46 2.39 1.61
22 2.08 1.77 3.98 5.13 3.79 3.56 3.29 3.49
31 2.96 2.48 ---- ---- 2.75 2.59 2.86 2.54
Jun 7 6.37 4.69 ---- ---- 7.31 6.66 6.84 5.68
13 5.49 4.62 ---- 4,36 3.77 4.93 4.20
20 3.51 3.38 3.51 3.38
26 5.28 3.30 5.28 3.30
Jul 4 8.23 4.76 ---- ---- 8.30 5.90 8.27 5.33
11 6.77 5.70 6.77 5.70
18 7.21 6.87 ---- ---- ---- --- 7.21 6.87
24 6.98 5.16 6.98 5.16
31 7.49 5.15 7.49 5.15
Aug 8 5.18 3.58 5.18 3.58
16 7.92 5.80 7.92 5.80
21 ---- 8.72 8.72
28 6.33 5.68 ---- ---- ---- --- 6.33 5.68
Sep 13 3.37 3.08 ---- ---- ---- -- - 3.37 3.08
Oct 3 4.01 4.34 4.01 4.34
9 4.24 2.65 4.24 2.65
24 4.94 2.99 4.94 2.99
31 5.32 4.24 5.32 4.24
Nov 7 2.06 1.13 ---- ---- ---- ---- 2.06 1.13
20 5.09 4.05 ---- ---- ---- ---- 5.09 4.05
26 4.34 4.30 ---- ---- ---- ---- 4.34 4.30
Dec 5 6.43 6.03 6.43 6.03
12 5.88 5.86 ---- ---- ---- ---- 5.88 5.86
-74-
Table 7 Ctn- Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Blue Plains station for indicated dates and depths
Date Surface Middle Bottom X X
(1975- (DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Feb 20 6.49 5.98 ---- ---- ---- ---- 6.49 5.98
28 8.76 6.55 --- ---- ---- ---- 8.76 6.55
Grand Means: DOC = 6.03 (n=36)
POC = 4.46 (n=37)
Ration 1.35
-75-
Table 8. Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Wilson Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975-
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Mar 1 5.68 1.53 4.18 ---- 1.62 1.20 3.83 1.37
15 8.89 0.95 10.19 1.74 10.19 1.45 9.76 1.38
21 6.20 9.84 8.60 12.32 6.71 18.00 7.17 13.39
29 13.24 2.45 13.39 3.49 12.84 3.85 13.16 3.27
Apr 11 4.39 2.10 ---- 0.99 ---- 1.00 4.39 1.37
19 3.68 2.10 3.56 2.57 2.60 2.25 3.28 2.31
26 4.25 2.38 4.70 3.77 3.89 4.50 4.28 3.55
May 2 3.45 1.43 2.78 1.17 3.14 1.72 3.13 1.44
8 3.47 2.31 . 3.78 1.74 3.67 2.81 3.64 2.29
17 2.65 1.62 2.51 2.09 3.48 2.03 2.88 1.92
22 3.67 1.99 3.11 2.35 3.10 2.32 3.30 2.22
31 2.67 1.58 2.45 2.17 2.73 2.03 2.62 1.93
Jun 7 3.92 2.63 5.03 2.63 4.84 2.92 4.60 2.73
13 3.69 2'.48 4.27 3.03 4.19 3.02 4.05 2.85
20 6.41 6.64 4.55 3.61 5.17 3.84 5.38 4.70
26 3.83 2.05 3.99 2.41 3.86 2.72 3.90 2.40
Jul 4 5.53 2.62 5.16 3.18 5.38 3.62 5.36 3.14
11 5.25 3.00 4.28 2.72 4.56 3.07 4.70 2.93
18 4.05 1.88 3.51 1.87 3.45 2.81 3.67 2.19
24 5.51 1.98 4.70 2.98 5.03 2.98 5.08 2.65
31 5.56 3.85 5.96 4.42 5.41 3.02 5.65 3.77
Aug 8 4.43 2.99 4.31 2.72 4.67 3.04 4.47 2.92
.16 6.10 2.96 5.74 3.39 6.33 4.71 6.06 3.69
21 4.14 3.29 5.85 3.30 4.89 3.63 4.96 3.41
28 3.98 2.37 4.14 1.92 5.32 2.49 4.48 2.26
Sep 13 3.53 2.75 3.04 2.42 4.40 3.74 3.66 2.97
Oct 3 3.24 1.43 3.23 1.30 2.24 1.43 2.91 1.39
9 2.62 0.90 2.35 1.12 2.35 1.25 2.44 1.09
24 3.55 2.01 3.86 2.43 3.90 3.66 3.77 2.70
31 3.23 1.47 3.19 1.78 2.75 1.28 3.06 1.51
Nov 7 1.18 2.78 2.27 1.27 2.34 3.17 1.93 2.41
20 3.52 1.93 5.96 1.80 4.80 2.27 4.76 2.00
26 2.65 0.91 2.83 1.40 2.51 1.75 2.67 1.36
Dec 5 3.25 1.79 3.77 1.79 3.04 1.97 3.36 1.85
12 2.88 1.25 2.94 1.21 2.76 1.71 2.86 1.39
Table 8 Ctn- Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg Clliter) for Wilson Bridge station for indicated dates and depths
Date Surface Middle Bottom X X
(1975- (DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976)
Feb 20 2.26 1.14 3.13 2.32 2.41 2.87 2.60 2.11
28 3.35 2.67 4.28 3.68 4.16 3.11 3.93 3.16
Grand Means: DOC = 4.37 (n=109)
POC = 2.71 (n=110)
Ratio 1.61
-77-
Table 9. Dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for Buoy 84 station for indicated dates and depths
Date Surface Middle Bottom X X
(1975- (POC
(DOC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
1976) )
Apr 11 2.11 1.45 3.88 2.28 2.20 1.66 2.73 1.80
26 3.09 3.19 3.76 2.52 3.71 1.00 3.52 2.24
May 2 4.00 1.69 3.18 2.17 3.85 2.98 3.68 2.28
8 3.95 2.39 4.99 1.71 3.44 2.61 4.13 2.24
17 2.96 1.54 3.11 1.99 2.67 1.99 2.92 1.84
22 3.14 2.10 3.84 2.82 2.26 3.60 3.08 2.84
31 1.70 2.19 2.62 1.79 2.54 3.66 2.29 2.55
Jun 7 5.70 2.98 5.75 3.92 5.70 3.21 5.72 3.37
13 5.41 1.99 4.75 5.67 6.25 5.75 5.47 4.47
20 4.30 3.59 3.65 2.81 4.13 3.72 4.03 3.38
26 5.31 3.04 4.09 2.94 3.58 3.28 4.33 3.09
Jul 4 5.16 2.02 5.58 2.87 5.58 1.72 5.44 2.21
11 5.21 2.74 5.03 2.74 5.32 4.20 5.19 3.23
18 4.44 3.04 5.34 2.46 3.90 2.47 4.56 2.66
24 4.41 2.76 2.26 2.07 4.59 2.98 3.76 2.61
31 5.29 3.44 4.66 3.00 5.17 3.43 5.04 3.29
Aug 8 5.06 3.11 5.50 3.15 4.92 4.46 5.16 3.58
16 5.11 2.62 4.45 2.82 7.98 3.49 5.85 2.98
21 5.23. 2.77 5.03 2.80 4.93 3.47 5.07 3.02
28 4.92 3.01 4.94 2.55 4.66 3.24 4.84 2.94
Sep 13 3.44 2.18 2.79 1.26 2.34 2.46 2.86 1.97
Oct 3 2.75 1.38 3.19 1.77 2.90 3.03 2.95 2.06
9 2.46 0.59 2.58 1.11 2.50 1.24 2.52 0.98
24 3.66 1.38 3.86 1.79 4.30 2.26 3.94 1.81
31 3.21 1.52 3.06 2.08 2.83 1.84 3.04 1.82
Nov 20 8.19 3.41 3.94 2.37 4.36 2.39 5.50 2.73
Dec 5 3.44 1.64 2.57 1.69 3.64 3.18 3.22 2.17
12 3.72 0.95 2.84. 1.34 3.27 2.05 3.28 1.45
Feb 20 1.24 2.76 1.96 1.89 2.05 2.50 1.75 2.39
28 4.47 2.68 ---- --- 3.70 3.65 4.09 3.17
Grand Means: DOC = 4.00 (n=89)
POC = 2.56 (n=89)
Ratio 1.56
Table 10. Total (TOC), dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) in surface water samples collected from indicated Potomac River
stations on February 15, 1976.
Station River
(DOC) (POC) (TOC)
James Rumsey Bridge Mile
Shepherdstown 183.7 2.96 2.42 5.38
Highway 27 above
Harpers Ferry 172.0 3.18 2.28 5.46
Highway 340 in
Harpers Ferry 171.0 2.38 2.16 4.54
Highway 340
Shenandoah River
Harpers Ferry -- 4.48* 5.80* 10.28*
Mountain Stream into
Shenandoah River from -
National Park _ 1.85* 1.44* 3.29*
Highway 340 below
Harpers Ferry 170.5 3.81 2.25 6.06
Highway 287 at
Brunswick 165.8 3.14 2.09 5.23
Point of Rocks Bridge 159.5 3.05 2.20 5.25
495 Bridge 120.0 2.23 1.61 3.84
Chain Bridge ` 101.1 1.91 1.56 3.47
Key Bridge 98.1 1.79 1.26 3.05
Memorial Bridge 96.8 2.06 1.58 3.64
14th Street Bridge 95.4 2.83 3.16 5.99
Nanjemoy 64.0 3.80 3.75 7.55
Riverside 55.8 3.92** 9.08** 13.00**
-79-
Table 10(continued). River
(DOC) (POC) (TOC)
Station Mile
Popes Creek 45.8 3.60 2.56 6.16
Colton Point 24.3 3.20 4.50 7.70
Piney Point 16.8 3.92 2.06 5.98
Point Look Out 0.0 3.49 2.00 5.49
X=2.96 X=2.34 X=5.30
DOC/POC=1.26
*Data for Shenandoah River just presented, not used to calculate means **Data suspect,
not used to calculate means
-80-
Table 11. Surface water monitoring of dissolved (DOC), particulate (POC), and
total (TOC) organic carbon concentrations (mg C/liter) for Chain Bridge station for
September 26, 1975 to September 28, 1975
Time (DOC) (POC) (TOC)
9/26 1800 4.59 9.69 14.28
9/27 0000 3.81 7.52 11.33
0730 4.65 6.58 11.23
1330 3.94 8.77 12.71
1930 4.87 6.94 11.81
9/28 1300 4.64 4.53 9.17
Avg. 4.42 7.34 11.76
DOC/POC Ratio 0.6
Table 13: Twenty-four hour monitoring of dissolved (DOC) and particulate (POC) organic carbon
Concentrations (mg C/liter) for Memorial Bridge station on June 24, 1975 to June 25, 1975
Time Surface Middle Bottom X X
(DOC) (POC) (DOC) (POC) (WC) ROC) (DOC) (POC)
1000 2.27 3.05 2.08 2.87 2.60 1.76 2.32 2.56
1100 2.63 2.11 2.12 1.31 2.15 2.00 2.30 1.81
1200 1.87 2.06 2.22 2.13 3.82 2.91 2.64 2.37
1300 2.29 1.27 3.91 4.10 2.13 2.50 2.78 2.63
1400 2.32 3.34 2.34 2.49 2.84 2.04 2.50 2.63
1500 2.27 2.81 1.98 2.63 2.59 3.12 2.28 2.86
1600 2.53 1.99 2.07 2.64 1.91 2.44 2.17 2.36
1700 2.03 2.03 1.90 2.32 2.32 2.72 2.09 2.36
1800 2.42 4.77 2.46 2.62 3.23 2.30 2.71 3.23
1900 1.31 3.31 3.79 4.22 1.26 1.93 2.12 3.16
2000 5.46 2.92 2.75 2.63 3.90 3.27 4.04 2.94
3.60 2.45 3.23 2.77 2.98 3.70 3.27 2.98
2100 3.36 4.13 ---- ---- ---- ---- 3.36 4.13
3.98 3.89 3.98 3.89
4.55 5.65 ---- ---- ---- ---- 4.55 5.65
2200 3.30 2.82 3.19 2.49 2.87 2.26 3.12 2.53
2300 5.26 3.78 2.97 2.98 3.17 3.63 3.80 3.47
0000 5.03 3.99 2.6.9 2.96 3.23 3.94 3.65 3.63
0100 3.73 2.98 2.87 2.81 3.02 2.06 3.21 2.62
0200 3.22 2.71 3.58 2.60 0.082 3.36 2.30 2.89
0300 2.69 2.56 2.47 2.27 2.44 2.48 2.54 2.44
0400 3.06 2.30 2.97 1.75 3.54 2.00 3.19 2.02
0500 2.88- 2.17 2.78 2.43 4.04 2.37 3.24 2.33
-83-
Table 13 . Twenty-four hour monitoring of dissolved (DOC) and particulate (POC)
organic carbon concentrations (mg C/liter) for Memorial Bridge station on June 24, 1975
to June 25, 1975
Surface Middle Bottom X X
Time
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
0600 2.67 2.21 1.76 2.31 3.29 2.12 2.58 2.22
0700 2.69 1.42 1.95 2.47 3.45 3.49 2.70 2.46
0800 2.94 2.97 2.67 3.12 2.91 2.48 2.84 2.86
0900 3.27 2.17 2.82 2.56 3.06 2.12 3.05 2.29
1000 3.41 2.40 3.99 2.87 4.68 3.12 4.03 2.80
-84-
Table 14. Transect of dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for the Potomac River at Memorial Bridge station on June
24, 1975
Station Surface Middle Bottom X X
(ft. from
(DOC) (POC) (DOC) (POC) (DOC) (POC) (DOC) (POC)
Va. shore)
0 3.55 2.09 3.55 2.09
100 3.43 1.73 4.15 2.43 3.79 2.08
200 2.57 1.84 2.73 2.14 2.65 1.99
300 2.45 1.48 2.42 3.16 2.44 2.32
400 3.00 2.25 3.64 2.81 3.32 2.53
500 2.81 2.70 3.04 2.01 2.93 2.36
600 2.47 1.92 2.90 2.06 2.69 1.99
700 2.15 1.53 1.90 1.44 3.66 2.10 2.57 1.69
800 3.60 1.95 3.19 3.36 2.60 2.28 3.13 2.53
900 4.99 3.39 3.66 2.24 3.38 2.80 4.01 2.81
1000 3.40 2.77 2.45 3.32 2.45 3.17 2.45
1100 2.64 2.75 3.72 2.04 4.17 2.73 3.51 2.51
1200 4.35 2.09 3.15 1.33 3.35 1.68 3.62 1.70
1300 3.37 2.30 2.62 2.37 2.69 2.44 2.90 2.37
1400 3.90 2.77 3.00 3.20 2.25 3.19 3.05 3.06
1500 3.69 3.04 2.93 2.33 2.41 2.31 3.01 2.56
1600 2.56 1.78 2.49 2.03 2.53 1.91
1700 3.48 2.20 3.48 2.20
Avg. 3.25 2.23 3.00 2.31 3.08 2.42 3.14 2.29
-85-
Table 15. Flow data of dissolved (DOC) and particulate (POC) organic carbon concentrations (mg C/liter) for indicated
Rock Creek stations for indicated dates
Date Rapids Mill Zoo Whitehurst
(1975-
Time (DOC) (POC) Time (DOC) (POC) Time (DOC) (POC) Time (DOC) (POC)
1976)
Nov 7 2.44 0.74 2.01 1.13
14 1000 2.50 1.30 1015 3.53 1.49 1030 3.29 1.49 1045 5.34 4.40
20 3.38 1.47 3.35 1.72 3.43 1.44
26 2.44 1.30 2.40 1.23 2.71 1.48
Dec 5 3.73 1.83 3.46 1.90 3.46 1.90
12 4.42 1.28 3.94 1.19 2.86 1.77
Jan 24 1030 2.15 1.18 1045 2.52 1.02 1100 3.83 1.03 1130 2.48 1.37
26 1450 6.67 7.29 1500 6.98 6.47 1515 6.95 5.82 1530 7.18 7.15
27 1300 9.06 4.93 1300 5.64 6.67 1245 4.97 5.82 1230 8.37 7.29
31 0945 6.65 3.38 1 000 6.37 3.96 1015 6.09 3.11 1030 4.76 2.79
Feb 7 1000 3.83 1.84 1015 3.15 1.53 1030 3.98 1.18 1045 3.05 1.59
15 1855 3.20 1.48 1840 3.01 2.11 1820 3.27 3.53
20* 1120 3.14 2.31 1130 2.45 2.45 1145 2.34 2.05 1200 2.26 1.77
28 3.84 1.31 3.16 2.11 3.70 1.38 2.47 1.34
* Two samples were collected where Rock Creek empties into the Potomac River. The substance in the water
resembled antifreeze.
(DOC) (POC)
4.30 3.33
3.88 2.66
Table 16. Streetrunoff data of dissolved (DOC) and particulate (POC) organic carbon concentrations (mg C/liter) for indicated
Falls Church, Virginia stations for indicated dates
Station February 1, 1976 February 13, 1976 February18 1976 February 22, 1976
Time (DOC) (POC) Time (DOC) (POC) Time (DOC) (POC) Time (DOC) (POC)
7000 Vagabond Drive 11.07 1045 2.07 5.60
2300 66.15* 19.35 ---- ---- ---- 1835 5.00
(Street runoff) 31.94 1050 4.05 7.26
Vagabond Drive &
Slade Run above ---- ---- ---- ---- ---- ---- ---- ---- ---- 1048 1.29 5.07
construction site
Vagabond Drive & 1045 5.67 21.44
Slade Run at ---- ---- ---- ---- ---- ---- ---- ---- ---- 1050 6.77 28.94
construction site 1300 9.42 6.89
Vagabond Drive &
Slade Run below ---- ---- ---- ---- ---- ---- ---- ---- ---- 1047 8.41 20.14,
construction site
Slade Run & 2300 1.00* 11.28 2105 25.03* 14.59
Roundtree 2300 1.50* 18.54
Slade Run &
2300 7.60 9.11 2300 11.56 15.99 1740 7.80 16.67 --- --- ---
Hickory Hill Road
1754 6.75 8.85
2310 19.82 27.22
Loehmann's Plaza 1845 6.75 11.13
2300 2.20 20.40 2321 17.83 25.57 --- --- ---
(7-11 storm drain) 1902 6.58 6.00
2323 12.51 53.64*
1908 8.09 6.11
Loehmann's Plaza 2322 17.15 17.24 1756 5.70 9.03
---- ---- ---- --- --- ---
corner by Citgo 2328 17.15 15.44 1848 5.76 7.92
2315 41.59* 45.33* 1759
Loehmann's Plaza 2300 8.91 10.53
2.13 7.44 2316 36.25* 48.87* 1850 --- --- ---
Dart Drug parking lot 9.43 9.96
2319 34.83* 55.38*
* by extrapolation
Table 17. Storm sewer dissolved (DOC) and particulate (POC) organic carbon concentrations
(mg C/liter) for Garfield Street station for indicated dates.
Date Time (DOC) (POC)
Jul 9 1705 39.67 22.50
1720 44.33 15.00
1725 42.17 8.50
1740 33.33 8.25
Jul 15 ---- 6.33 6.80
Table 18. Land runoff data of dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for indicated Washington, D.C. stations for February 18, 1976.
Station Time (DOC) (POC)
2030 28.96 51.65
Washington Monument
2035 13.11 8.50
2000 20.45 28.50
Bicentennial Park
2025 14.15 7.69
Table 19. Storm sewer dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for New Mexico Avenue station for indicated dates .
Date Time (DOC) (POC)
Jul 9 1659 37.17 21.40
1704 22.67 8.25
1713 19.83 4.75
1718 23.83 7.25
1730 21.17 5.50
1735 22.00 5.25
Jul 10 0610 10.73 17.20
0630 9.33 11.00
0633 7.58 6.80
0636 9.17 7.50
0639 8.83 10.00
0642 9.17 8.55
0645 10.86 7.50
0650 7.47 2.00
0655 7.33 9.50
0700 6.50 8.50
0705 8.77 8.80
0710 7.83 6.80
0715 7.67 7.50
Jul 15 ---- 6.60 4.80
Jan 26 1700 7.83 7.54
0735 4.37 1.86
Jan 27
1935 5.43 3.42
Feb 22 0933 25.57 23.30
0935 16.03 29.70
0940 14.29 20.38
0945 14.85 18.57
0950 13.84 14.26
0955 12.88 11.85
1000 11.26 10.50
1005 12.32 8.93
1010 10.75 11.57
1015 13.22 14.09
1030 12.88 23.52
1045 10.13 30.04
1100 9.06 17.80
1130 9.85 11.34
1200 10.07 9.49
1300 11.93 12.67
Table 20. Storm sewer dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for New York Avenue station for indicated dates.
Date Time (DOC) (POC)
Jul 15 ---- 7.77 13.00 Industrial
---- 6.50 8.00 Residential
---- 8.77 12.50 Residential
Feb 7 1100 9.52 1.19 TOC of scum 1781.47*
Feb 13 2128 71.26* 105.31* Mid-channel
2138 42.49* 75.91* Mid-channel
2155 31.82 89.55* Mid-channel
2205 44.23 62.02* Mid-channel
2215 41.50 21.08 Mid-channel
2128 58.86 ---- Industrial
Feb 15 1750 7.82 4.26 Mid-channel
Feb 22 1010 9.72 18.52 Mid-channel
1020 10.90 11.89 Industrial
1030 10.57 14.56 Industrial
1045 13.29 13.64 Industrial
1100 7.41 21.35 Industrial
1115 6.90 13.69 Industrial
1145 7.31 11.69 Industrial
1020 10.03 13.90 Residential
1040 10.60 13.18 Residential
1045 10.47 14.82 Residential
1100 7.69 23.25 Residential
1115 6.56 16.93 Residential
1145 5.15 13.80 Residential
Mar 5 1535 20.67 17.49 Mid-channel
1538 23.13 52.93* Industrial
1549 27.24 83.50* Industrial
1554 19.88 16.87 Industrial
1559 18.25 14.25 Industrial
1604 18.57 16.74 Industrial
1609 9.88 10.09 Industrial
1614 15.29 39.81 Industrial
1624 27.95 15.92 Industrial
1629 31.79 20.43 Industrial
1542 12.18 16.25 Residential
1549 10.92 17.26 Residential
1554 11.75 23.77 Residential
1559 13.42 15.36 Residential
1604 15.29 94.41* Residential
1609 18.09 15.09 Residential
1614 13.09 19.26 Residential
1619 14.92 19.26 Residential
1624 13.92 15.26 Residential
1629 11.08 14.25 Residential
* by extrapolation
-90-
Table 21. Dry flow (no overflow) concentrations of dissolved (DOC) and particulate (POC) organic
carbon (mg/l) for indicated combined sewer stations for indicated dates.
Date DES
DES #43
(1975- Time #24 (POC) Time (POC) RATIO
(DOC)
1976) (DOC)
May 8 ---- ---- ---- 1700 4.13 1.90 2.2
17 ---- ---- ---- 1530 5.63 2.39 2.4
Jul 15 ---- 26.11 23.80 ---- ---- ----
18.75
1859 36.71 0.5
41.72
Feb 18 ---- ---- ---- 1905 107.61 0.4
25.04
1914 49.19 0.5
104.93
Table 22. Overflow data of dissolved (DOC) and particulate (POC) organic carbon
concentrations (mg C/liter) for indicated combined sewer stations for indicated dates.
June 10, 1975 February 27,1976
Station DES No. Time DOC POC RATIO Time DOC POC RATIO
Northeast Boundry 24 1230 40.50 19.70 2.06 1230 25.41 39.95 0.64
(Armory)
Easby Point 34 1000 45.00 23.20 1.94 1300 Dry Dry
Kennedy Center 35 1130 46.20 34.80 1.33 1400 26.97 49.97 0.54.
30th & K Streets 38 1100 39.00 21.20 1.84 1600 5.50 6.60 0.83
Potomac & Waters 43 1045 47.10 21.10 2.23 1530 34.58 50.18 0.69
Piney Branch 70 -No Discharge- ---- 1130 33.64 39.02 0.86
(@ Rock Creek) Means 45.6 24.0 1.9 25.2 37.1 0.7
Table 23. Time of water sample collection for indicated stations for indicated dates
Date
Chain Key Memorial 14th Street Blue Wilson Anacostia
(1975- Buoy 84
Bridge Bridge Bridge Bridge Plains Bridge River
1976)
Mar 1 ---- 1030 1100 1130 1200 1250
15 1115 1145 1215 1240 1330 1315
21 ---- 1330 1400 1430 1500 1530
29 1245 1315 1340 1400 1500 1440
Apr 6 ---- ---- ---- ---- ---- ---- ---- 1300
11 1300 1200 1230 1200 1130 1115 1030 1500
19 1230 1200 1115 1045 1000 0930 ---- ----
.26 1645 1615 1600 1545 1515 1500 1430 1720
May 2 1600 1530 1515 1500 1440 1420 1400 1645
8 1500 1430 1415 1400 1330 1315 1250 1600
17 1400 1330 1315 1300 1245 1230 1030 1445
22 1300 1245 1230 1210 1145 1130 1100 1340
31 0815 0800 0745 0730 1100 1030 0945 1145
Jun 7 1015 0945 0915 0900 1100 1115 1145 0840
13 1245 1215 1145 1130 1115 1100 1030 1330
20 1230 1145 1115 1050 1030 1020 1000 1315
24 - See Table
26 1400 1330 1315 1250 1230 1215 1145 1445
Jul 4 1630 1545 1500 1430 1415 1400 1335 1300
11 1330 1300 1235 1220 1150 1130 1100 1400
18 1300 1230 1215 1200 1130 1115 1045 1345
24 1245 1200 1145 1130 1115 1100 1030 1345
31 1620 1600 1545 1530 1515 1500 1400 ----
Aug 8 1610 1540 1520 1500 1445 1430 1400 1650
16 1350 1320 1300 1240 1215 1150 1130 1415
-93-
Table 23. Time of water sample collection for indicated stations for indicated dates
Date Chain Key memorial 14th Street Blue Wilson Anacostia
Buoy 84
(1975- Bridge Bridge Bridge Bridge Plains Bridge River
1976)
Aug
1330 1300 1230 1215 1200 1130 1100 1925
21
28 --- --- --- --- --- --- --- ---
Sep 13 ---
26 See Table
27 See Table
28 1300
Oct 3 1550 1500 1445 1430 1410 1400 1330 1620
9 1230 1150 1130 1115 1045 1030 1000 1320
24 1530 1500 1430 1400 1345 1330 1300 1600
31 1230 1200 1130 1100 1045 1030 1000 1330
Nov 7 1500 1445 1430 1415 1345 1330 ---- 1530
20 1430 1400 1330 1315 1245 1230 1200 1515
26 --- --- --- --- --- --- --- ---
Dec 5 1450 1420 1400 1345 1315 1300 1230 1520
12 1350 1320 1300 1250 1230 1215 1200 1420
Jan 24 1400 1300 1230 1200 ---- ---- ---- 1330
26 --- ---
31 1230 1205 1145 1130 ---- ---- ---- 1100
Feb 7 1320 1300 1245 1230 --- ---- ---- 1115
14 1230 1200 1145 1130 ---- ---- ---- ---
15
20 1640 1600 1520 1500 1455 1440 1330 1730
28 1330 1305 1245 1230 1210 1200 1135 1440
-94-
Table 23. Time of water sample collection for indicated stations for indicated dates
Date
Roosevelt Haines Alexandria
(1975- Buoy 71 Buoy 73 Buoy 76 Buoy 77 Buoy 88
Bridge Point Power Plant
1976)
May 17 1120 1100
Jun 7 1300
Aug 16 1100
Nov 7 1300
Jan 24 1245 1215
31 1155 1115
Feb 7 1215
20 1350 1410
28 1100
Table 24. Daily precipitation data for Washington, D.C. National Airport for February 1975 to February 1976
Day February March April May June July August
1 0.03 T T T 0 0 0.70 0 0.39 0 0 0 0 0
2 0.10 1.60 T T 0 0 T 0 T 0 0 0 0 0
3 0 0 0 0 0.09 0 0.09 0 0.17 0 0.24 0 0 0
4 0.36 4.10 0 0 0 0 0.43 0 T 0 0 0 0.07 0
5 0.22 0.10 0 0 0 0 T 0 0.40 0 0 0 T 0
6 0.06 0 0 0 0 0 0.25 0 T 0 0 0 0.38 0
7 0 0 0.06 0 0 0 0 0 T 0 T 0 T 0
8 0 0 T T 0 0 0 0 0 0 0 0 0 0
9 T T 0 0 0 0 T 0 0 0 T 0 0
10 0 0 0.16 0.30 T T 0 0 0 0 0.83 0 0 0
11 0 0 0 0 0 0 0 0 0.22 0 0.06 0 0.08 0
12 0.31 0 0.57 0 0 0 0.26 0 0.24 0 0.02 0 0 0
13 T T 0.28 0 0 0 0.15 0 T 0 3.13 0 T 0
14 0 0 0.75 T 0.03 0 0 0 0 0 1.73 0 0.41 0
15 0 0 0 0 0.56 0 0.20 0 0 0 0.02 0 0.06 0
16 0.02 0 0.14 T T 0 0.13 0 0.44 0 0.03 0 0.13 0
17 0.10 0 0.36 0 0 0 T 0 0 0 T 0 0.44 0
18 T 0 T 0 0.05 0 T 0 0 0 0 0 0 0
19 T 0 1.23 0 T 0 0 0 T 0 0 0 0 0
20 0 0 T 0 0 0 0 0 0 0.57 0 0 0
21 0 0 0 0 0 0 0 0 0 0 0 0 0 0
22 0 0 0.03 0 0 0 2.20 0 0 0 0 0 T 0
23 0.21 0 0 0 T 0 0.14 0 0 0 0 0 0.35 0
24 0.15 0 1.35 0 0.24 0 0.09 0 0 0 0.40 0 0.02 0
25 0 0 0 0 0.57 T 0 0.03 0 T 0 0 0
26 0 0 0 0 0 0 T 0 0.20 0 0 0 T 0
27 0 0 0 0 0 0 T 0 0.05 0 0 0 0 0
28 0 0 T 0 0.28 0 0 0 0.01 0 0.13 0 0 0
29 0.02 0 0.31 0 0 0 T 0 0 0 0 0
30 0.38 0 T 0 T 0 0 0 0 0 0.38 0
31 0 0 0.07 0 0 0 1.22 0
1.56 5.80 5.33 0.30 2.13 T 4.71 0 2.15 0 7.16 0 3.54 0
T is unmeasurable precipitation * is water equivalent in inches ' is snow, ice in inches
Table 24. Daily precipitation data for Washington, D.C. National Airport for February 1975 to February 1976
Day September October November December January February
1 1.66 0 0 0 0 0 0.26 0 0.45 T 0.50 0
2 0 0 T 0 T 0 0 0 0 0 0.15 0.90
3 0 0 0 0 0 0 0 0 0.35 0 T T
4 T 0 0 0 0 0 0 0 0 0 0 0
5 0 0 T 0 0 0 0 0 0 0 T 0
6 0.28 0 T 0 0 0 0.08 0 0 0 0.02 T
7 0.08 0 0 0 T 0 T 0 0.37 0 T T
8 0 0 0.44 0 0.40 0 0.10 0.40 0.09 T 0 0
9 0 0 0.76 0 0 0 0.41 0 0 0 T T
10 0 0 0.01 0 0.10 0 0 0 0 0 0 0
11 0.18 0 0.05 0 0 0 0 0 0.06 T T 0
12 0.30 0 0 0 1.26 0 0 0 0 0 0 0
13 0 0 0 0 0.26 0 0.06 0 0.02 0 0.08 0
14 0 0 0 0 T 0 0 0 T 0 0.01 0
15 0 0 0 0 0 0 T 0 0 0 0 0
16 T 0 T 0 0 0 0.02 0 0 0 0 0
17 0 0 0.82 0 0 0 0 0 0 0 T 0
18 0.70 0 0.01- 0 0 0 0 0 0 0 0.24 0
19 0.08 0 T 0 0 0 0 0 0 0 0 0
20 T 0 0 0 0 0 0 0 0.02 T 0 0
21 T 0 0 0 0.03 0 T T 0.01 0.10 0 0
22 0.51 0 0 0 0 0 0 0 0 0 0.55 0
23 1.88 0 0 0 0 0 0 0 0 0 0 0
24 1.11 0 T 0 0 0 0 0 0 0 0 0
25 3.46 0 0.06 0 0 0 0.25 T 0 0 0 0
26 2.12 0 0.01 0 0 0 0.86 0 1.32 0 T 0
27 0 0 T 0 T 0 T 0 0.87 T 0 0
28 0 0 0 0 0 0 0 0 T T 0 0
29 0 0 0.01 0 0 0 0 0 T T 0 0
30 0 0 0.21 0 0 0 0.32 0 T T
31 0 0 1.68 0 T T
12.36 0 2.38 0 2.05 0 4.04 0.40 3.56 0.10 1.55 0.90
Table 25. Miscellaneous physical data from the Little Falls, Maryland station of the Potomac
River for the sampling dates of the study period
Subsequent Three
Date
Discharge Day Accumulation
(1975-
ft.3/sec. of Rainfall
1976)
in inches
Mar 1 20800 0
15 19790 1.60
21 165600 1.23
29 20650 0
Apr 11 11380 0
19 8690 0.05
26 17310 0.81
May 2 26710 1.01
8 30420 0.25
17 17540 0.33
22 13590 0
31 10250 0
Jun 7 16070 0.40
13 13700 0.46
20 60360 0
26 49390 0.03
Jul 4 63530 0.24
11 96960 0.83
18 96060 0.05
24 77860 0
31 45290 0.13
Aug 8 34410 0.38
16 45970 0.47
21 58050 0
28 36280 0
Sep 13 4050 0.48
Oct 3 15960 0
9 10060 0.44
24 20650 0
31 10150 0.22
Nov 7 73500 0
20 11480 0
26 8600 0
Dec 5 6270 0
Table 25. Miscellaneous physical data from the Little Falls, Maryland station of the
Potomac River for the sampling dates of the study period
Subsequent Three
Date
Discharge Day Accumulation
(1975-
ft.3 /sec.' of Rainfall
1976)
in inches
Dec 12 7790 0.41
Jan 24 7010 0.11
31 25740 0
Feb 7 14120 0.02
15 14540 0.09
20 20780 0.24
28 11280 0
Table 26, Times of high and low waters for indicated Potomac River and Anacostia
River stations for indicated dates
Date Wilson Buoy 84 Blue Plains Anacostia
(1975- Bridge
1976) High Low High Low High Low High Low
1 1029 1649 1037 1702
15 0741 1701 0849 1714
21 1447 0843 1455 0856
29 0917 1619 0925 1632
Apr 11 0723 1425 0708 1410 0731 1438 0740 1448
19 1305 0825 1313 0838 /
26 2023 1507 2008 1452 2031 1520 2040 1530
May 2 1227 2007 1214 1952 '1237 2020 1246 2030
8 1741 1243 1726 1228 1749 1256 1758 1306
17 1211 1937 1156 1922 1219 1950 1228 2000
22 1741 1155 1726 1140 1749 1208 1758 1218
31 1153 0637 1138 0622 1201 0650 1210 0700
Jun 7 0523 1325 0508 1310 0531 1338 0540 1348
13 0947 1749 0932 1734 0955 1802 1004 1812
20 0429 1201 0414 1146 0437 1214 0446 1224
26 0917 1631 0902 1616 0925 1644 0934 1654
Jul 4 1559 0949 1544 0934 1607 1002 1616 1012
11 0835 1607 0820 1552 0843 1620 0852 1630
18 1553 1043 1538 1028 1601 1056 1610 1106
24 0823 1531 0808 1516 0831 1544 0840 1554
31 1259 1931 1244 1916 1307 1944 1316 1954
Aug 8 2017 1455 2002 1440 2025 1508 2034 1518
16 1505 1001 1450 0946 1513 1014 1522 1024
21 0717 1349 0702 1334 0725 1402 0734 1412
28
Sep 13
Oct 3
24
31
7 1035 1713 1043 1726 1052 1736
20 0817 1443 0802 1428 0825 1456 0834 1506
26
Dec 5 0905 1601 0850 1546 0913 1614 0922 1624
12 1505 0907 1450 0852 1513 0920 1522 0930
-100-
Table 26. Times of high and low waters for indicated Potomac River and Anacostia
River stations for indicated dates
Date Wilson Bridge Buoy 84 Blue Plains Anacostia
(1976) High Low High Low High Low High Low
Jan 24 1405 0819 1422 0842
31 0741 1455 0758 1518
Feb 7 1235 1901 ---- ---- ---- --- 1252 1924
15 0723 1355 --- ---- ---- -
20 1117 1913 1102 1858 1125 1926 1134 1936
28 0647 1355 0632 1340 0655 1408 0704 1418
Table 26. Times of high and low waters for indicated Potomac River stations for indicated dates
Date Chain Key Memorial 14th Street
(1975- Bridge Bridge Bridge Bridge
1976) High Low High Low High Low High Low
Mar 1 ---- ---- 1046 1712 1036 1712 1036 1708
15 0908 1734 0858 1724 0848 1724 0848 1720
21 ---- ---- 1504 0906 1454 0906 1454 0902
29 0944 1652 0934 1642 0924 1642 0924 1638
Apr 11 0750 1458 0740 1448 0730 1448 0730 1444
19 1332 0858 1322 0848 1312 0848 1312 0844
26 2050 1540 2040 1530 2030 1530 2030 1526
May 2 1256 2040 1246 2030 1236 2030 1236 2024
8 1808 1316 1758 1306 1748 1306 1748 1302
17 1238 2010 1228 2000 1218 2000 1218 1956
22 1808 1228 1758 1218 1748 1218 1748 1214
31 1220 0710 _ 1210 0700 1200 0700 1200 0654
Jun 7 0550 1348 0540 1348 0530 1348 0530 1344
13 1014 1822 1004 1812 0954 1812 0954 1808
20 0456 1234 0446 1224 0436 1224 0436 1220
26 0944 1704 0934 1654 0924 1654 0924 1650
Jul 4 1626 1022 1616 1012 1606 1012 1606 1008
11 0902 1640 0852 1630 0842 1630 0842 1626
18 1620 1116 1610 1106 1600 1106 1600 1102
24 0850 1604 0840 1554 0830 1554 0830 1550
31 1326 2004 1316 1954 1306 1954 1306 1950
Aug 8 2044 1528 2034 1518 2024 1518 2024 1514
16 1532 1034 1522 1024 1512 1024 1512 1020
21 0744 1422 0734 1412 0724 1412 0724 1408
28 ---- ---- --- ---- ---- ---- --- ---
Sep 13 ---- ---- ---- --
Oct 3
9
24
31
Nov 7 1102 1746 1052 1736 1042 1736 1042 1732
20 0844 1516 0834 1506 0824 1506 0824 1502
26 ---- --- ---- ---- ---- ---- ---- ---
Dec 5 0932 1634 0922 1624 0912 1624 0912 1620
12 1532 0940 1522 0930 1512 0930 1512 0926
-102-
Table 26. Times of high and low waters for indicated Potomac River stations for indicated
dates
Date Memorial 14th Street
Chain Bridge Key Bridge
(1976) Bridge Bridge
High Low High Low High Low High Low
Jan 24 1432 0852 1422 0842 1412 0842 1412 0838
31 0808 1528 0758 1518 0748 1518 0748 1514
Feb 7 1302 1934 1252 1924 1242 1924 1242 1920
15 0750 1428 0740 1418 0730 1418 0730 1414
20 1144 1946 1134 1936 1124 1936 1124 1932
28 0714 1428 0704 1418 0654 1418 0654 1414
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