Donaldson Run Stream Restoration – Tributary B
Frequently Asked Questions (FAQs)
What is stream restoration? Put simply, stream restoration creates a stream that is in
balance with stormwater flows from its watershed. The result is a stable, self-
maintaining stream channel that can dissipate energy along its flow path and balance
the processes of erosion and sediment deposition.
Why do a stream restoration project? Why not just leave the stream as it is?
Donaldson Run has been impacted by stormwater runoff and direct manipulation of the
channel, causing excessive erosion along the stream channel. There are several
compelling reasons to do a stream restoration, sooner rather than later:
• Protect the sanitary sewer line. The stream erosion has uncovered the sanitary
sewer line in several places, and even completely eroded beneath the sewer line
in some locations. This sewer line was originally buried about three feet below
the stream channel bottom, but the stream has eroded down several feet over
the past 50 years. Exposed sewer lines along Donaldson Run have been broken
several times in recent years, and such breaks have caused leaks of untreated
sewage into the stream.
• Reduce sediment pollution and protect private property. Sediment that is
eroded from the stream degrades Donaldson Run, the Potomac River and the
Chesapeake Bay. Sediment and the nutrients carried with it are major pollutants
which cause a variety of problems in water bodies, such as reducing dissolved
oxygen, blocking sunlight from water, and smothering aquatic life. For these
reasons, the U.S. Environmental Protection Agency’s Chesapeake Bay Program
has recognized urban stream restoration as a key component of the plan to
restore the Chesapeake Bay watershed.
• Improve stream health. By creating a stable, self-maintaining stream channel,
the quality of the stream environment will be significantly improved. The
excessive erosion and sediment deposition that currently degrade stream habitat
will be eliminated, and the physical features of the stream channel that provide
good habitat for aquatic organisms will be greatly enhanced.
• Improve long-term health of the stream valley forest. The stream erosion
continues to undermine trees along the stream bank, and a substantial number of
mature trees have fallen into the stream or across the trail in recent years. Many
of the trees that will be removed by the restoration project are trees that are
already undermined by existing stream erosion and are likely to fall or die. Many
additional trees near the channel are likely to be undermined soon as the erosion
process continues. The restored stream channel will be stable, and, as a result,
the remaining trees and new trees planted after restoration will be protected.
• Protect the nature trail. Erosion is threatening the nature trail through the park
in several places.
How did this project get started? The Donaldson Run Civic Association received
Neighborhood Conservation Funding in 2001 to study Donaldson Run and identify
potential stream improvements. Residents were concerned about erosion in the stream,
which degrades water quality and in-stream habitat, and threatens nearby trees and
trails. A stream restoration project on Tributary A was completed in 2006. Additional
NCP funding was requested for Tributary B.
Who is working on this project? The project team is composed of County staff from
Department of Environmental Services, the Department of Parks, Recreation and
Community Resources, and the consultant team. An advisory group has been formed to
advise the project team. This advisory group includes representatives from the civic
association, and one representative from each of the Urban Forestry Commission, the
Parks and Recreation Commission, the Environment and Energy Conservation
Commission, and Arlingtonians for a Clean Environment.
Where else, especially in the Northern Virginia area, has the County’s consultant
completed stream restoration projects? The consultant hired for the project,
Vanasse, Hangen, Brustlin, Inc. (VHB), did the design work for the stream restoration
on Tributary A of Donaldson Run.
The County has installed rocks (rip-rap) along several sections of the stream in
the past, but that hasn’t fixed the erosion problems. How will this project be
different? This project is different from the previous attempts to stabilize the stream. It
involves careful study and analysis of the stream channel and watershed prior to doing
any work. By better understanding the stream and the amount of water flowing in it,
modern techniques lead to design of a stable channel shape that will be self-
maintaining. The new design of the stream channel will allow the stream to dissipate
energy along its flow path, without eroding the channel or negatively impacting
downstream areas, so the stream channel will maintain its shape.
Why was Donaldson Run selected as one of the first streams for stream
restoration? In the Watershed Management Plan, Donaldson Run was noted as
having some of the most severe erosion problems among all streams in the County.
The stream was also noted as having a good potential for restoration, given its location
in a park.
What if there is future development in the Donaldson Run watershed, increasing
the stormwater runoff, after the stream restoration is completed? The Donaldson
Run neighborhood, along with much of the watershed, is mostly built-out. Large-scale
new development in the watershed is unlikely, although a few large, relatively
undeveloped lots do remain, such as Missionhurst property. Any larger scale new
development projects that might occur will be required to install stormwater controls that
will help protect the restored stream. The more common form of development occurring
in the watershed today and likely to continue into the future is re-development of
individual residential lots. Lot-by-lot residential home expansion or replacement with
larger homes will likely increase impervious cover and stormwater runoff in a gradual
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manner over the long-term. However, the new stream configuration will allow the
stream to dissipate energy more effectively to accommodate some of this increased
flow. In addition, it is anticipated that the gradual nature of this increase in runoff,
coupled with evolving stormwater management requirements and ongoing watershed
initiatives that encourage techniques to reduce stormwater runoff from existing homes,
will help to minimize any negative future impacts on the restored stream.
What if steps are taken to reduce runoff into Donaldson Run in the future? Would
this mean the restoration project could be scaled back to some extent? Reducing
stormwater runoff is a goal for the future, but it will take time. At present, a stream
restoration program that results in stable systems that can handle current levels of
runoff is an important watershed management tool, along with efforts to reduce
stormwater runoff and pollution from both existing and new development. If runoff is
reduced in the future, the improved stream channels will be made even more effective.
What is the timeline for the project? The approximate timeline follows:
Advisory Group Meeting - November 5, 2009
Stream Walk with Consultant - Nov 14, 2009
DRCA Meeting - December 2, 2009
Plans revised based on community, staff, and advisory group input
Second Advisory group meeting/DRCA meeting
Final Design, Cost Estimates, Permitting
Construction – Fal/Winterl, 2010
How will the project impact neighbors and users of the park (noise, access, etc)?
Construction equipment will be used in the stream restoration project, to reshape the
stream channel, install sanitary sewer lines, and move heavy items, such as rocks.
County staff will work with the community to minimize disturbance as much as possible.
One advisory group member pointed out that that remodeling a house is a good
metaphor for a stream restoration project: There is some disturbance and mess while
the remodeling takes places, but the end goal should be a drastic improvement that is
worthy of the disturbance.
What type of equipment will be used for the project?
Some heavy equipment, such as backhoes, will have to be used in restoring the stream
channel. Disturbance to neighbors will be minimized as much as possible, and great
efforts will be made to protect trees and plants from damage from the equipment. This
will be done, in part, by choosing a contractor with experience operating in wooded park
environments such as those along Donaldson Run.
Will this project impact any of the property owners with flooding of basements,
etc? The stream valley is fairly steep and the homes sit at a higher elevation than the
stream, so flooding will not be an issue. However, computer modeling is conducted
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using the proposed stream configurations, to make sure that the new stream
configuration does not cause flooding. The stream restoration project will enhance the
value of the homes along the stream channel, by stabilizing the stream channel.
Will a tree inventory be conducted as part of the project? Yes, the trees will be
inventoried and the proposed stream channel will be adjusted where possible to protect
mature trees that are identified as being of particular interest to residents and park
How is the loss of trees going to be handled, and how are the trees going to be
replaced? Some trees along the stream channel will have to be removed in the course
of re-configuring the stream channel. However, many of the trees that are close to the
stream banks are already endangered due to the stream erosion. The community will
have an opportunity to identify trees that they would like to see preserved, without
compromising the success of the project, and many trees and plants, including some
larger trees where appropriate, will be planted following the restoration project.
What types of plants will be used in re-vegetating the stream banks after the
project? The stream valley is mostly shaded, and shade-tolerant native species of
grasses, shrubs, and trees will be used.
Project web site:
For more information, please contact Larry Finch of the Donaldson Run Civic
Association at email@example.com or 703-528-6349 or Aileen Winquist with Arlington
County at firstname.lastname@example.org or 703-228-3610.
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