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Total Area: 15,552 acres (24.3 mi2)
Average Imperviousness: 40%
Population: 195,267
Population Density: 8,035/mi2
Wetlands: 859 acres

Forest Cover: 11.3% Deciduous: 346.5 acres
Coniferous: 53.4 acres
Mixed: 270.4 acres
Shrub/Scrub: 128.9 acres
Local Watershed Group: Groundwork Anacostia, Friends of Dueling Creek,
Friends of Quincy Run

The 24.3 square mile 'Tidal River area' is defined as all of the lower Anacostia watershed area downriver of the Northwest Branch/Northeast Branch confluence, excluding Lower Beaverdam Creek, Watts Branch, Fort Dupont tributary, Pope Branch and Hickey Run; all of which are individual subwatersheds. The tidal area includes the following eight small tributaries, seven of which are located on the east-side of the river: Quincy Manor Run, Dueling Creek, Nash Run, Piney Run, Fort Chaplin, Fort Davis, Fort Stanton and Stickfoot. In addition, the tidal Anacostia River has been subdivided into the following three relatively discrete segments: 1) Upper (i.e., Northwest/ Northeast Branch confluence downriver to the Benning Road Bridge), 2) Middle (i.e., Benning Road Bridge downriver to the 12th Street Bridge) and 3) Lower (i.e., 12th Street Bridge downriver to the Potomac River confluence).


Within its relatively small 176 square mile drainage area, the Anacostia watershed includes portions of three political jurisdictions (District of Columbia (30.2 mi2, 17.2 percent), Montgomery (60.8 mi2, 34.4 percent) and Prince George's counties (85.2 mi2, 48.4 percent) and two physiographic provinces (Piedmont Plateau and Atlantic Coastal Plain). The Anacostia River is formed by two major tributaries, the Northwest and Northeast Branches, and includes direct tidal drainage from several small to medium size tributaries. Downstream of the confluence of these two streams, the Anacostia is a largely channelized, freshwater tidal river, which flows approximately 8.4 miles before joining the Potomac River. The Anacostia River has been classified by the District of Columbia as 'A' (Primary Contact Recreation), 'B' (Secondary Contact Recreation and Aesthetic Enjoyment), 'C' (Protection, and Propagation of Fish, Shellfish and Wildlife), 'D' (Protection of Human Health Related to Consumption of Fish and Shellfish), and 'E' (Navigation) waters.

Dominant Land Uses: Almost 100% of the watershed has been developed. High density residential apartment development, comprising approximately 43% of the total land area, is the single largest land use in the tidal area.

Hydrography: The hydrology of the entire Anacostia tributary system may be broadly characterized as being flashy (i.e., quick flow response to rainfall); whereas, the tidal river portion can be described as being sluggish with an average estimated water residence time on the order of 23 to 28 days. Under periods of extreme low flow, this residence time can be two to three months in duration. Mean daily inflow into the tidal river is approximately 138 cubic feet per second (i.e., 61,934 gallons per minute). As previously inferred, the Northwest and Northeast Branches contribute approximately 93 percent of the river flow. The mean daily baseflow of the Northwest and Northeast Branches is 58 and 70 cubic feet per second (cfs), respectively. The sluggish nature of the tidal river causes it to act as a very effective sediment trap. It has been estimated that approximately 85 percent of the incoming sediment load is deposited in the tidal river and remains trapped there.

Tidal River Fish Community: Although the resident fish community in the Anacostia River has changed dramatically over the years, it remains surprisingly diverse. The sample provisional fish species list indicates which species have been collected in the tidal river. Currently, 50 resident and migratory species are present. Historically, anadromous fish species (e.g., herring, shad, and striped bass) have migrated en masse from the Atlantic Ocean and Chesapeake Bay into the Anacostia River and its tributaries to spawn. During the past four decades, their annual upstream migrations have been largely prevented by over two-dozen unintentional and man-made barriers located primarily along the lower portions of tributaries such as the Northwest and Northeast Branches, Paint Branch, Indian Creek, Lower Beaverdam Creek, Sligo Creek and Watts Branch. It should be noted that while the amount of Anacostia tributary available habitat area has been steadily increasing over the last few years, the strength of associated herring runs has been generally declining. Although natural factors such as cold spring water temperatures and lower than average number of freshets may be contributing to some of the weaker than expected herring runs, other factors such as the continuing decline in broodstock (through commercial overfishing in and along Atlantic coast waters) are equally important. In fact, in 2006 NOAA's National Marine Fisheries Service listed both the alewife and blueback herring as species of concern.

Tidal and Non-Tidal Wetlands: Wetlands are a critical part of a watershed's ability to filter out pollutants, as well as provide wildlife and waterfowl habitat. Three general wetland types are present in the watershed: 1) Palustrine (i.e., marshes, swamps and small shallow ponds under 20 acres in size which are dominated by trees, shrubs and persistent emergents); 2) Riverine (i.e., freshwater tidal rivers and non-tidal streams that contain flowing water at least periodically); and 3) Lacustrine (i.e., lakes, ponds and reservoirs with less than 30 percent coverage by wetland emergents, trees or shrubs). To date, more than 90 percent of the Anacostia watershed's tidal wetlands and nearly 70 percent of its non-tidal wetlands have either been destroyed or altered. It is estimated that more than 6,500 acres of tidal and non-tidal wetlands may have been lost from the watershed due to historic land conversion to agriculture, sand and gravel mining, urban development, and filling and dredging within and along the tidal river. Of this total amount, approximately 4,000 acres of non-tidal wetlands have been lost, with more than 90 percent of this loss coming from the Coastal Plain area. Approximately 3,208 acres of wetlands remain within the Anacostia, with the vast majority present in the Coastal Plain portion of the watershed. The loss of tidal wetlands in the watershed has been even more pronounced. The U.S. Army Corps of Engineers estimated that approximately 2,500 acres of tidal emergent wetlands have been destroyed in the Anacostia River between Bladensburg and the confluence with the Potomac River. Even with restoration projects such as Kenilworth Marsh, Kingman Lake, Heritage Island, River Fringe Wetlands, Bladensburg Marina and Anacostia Site 11 representing approximately 139 acres, total, less than 180 acres presently remain.

Condition Summary: Major restoration efforts since 1987 have begun to slowly improve conditions in both the river and at the local stream level. From stream restoration, reforestation, wetland restoration/creation and stormwater retrofitting to repairing leaking sewers and reducing the quantity and impact of combined sewer overflows, governmental agencies, often in partnership with environmental and community groups, have, since 1987, implemented hundreds of restoration projects. The collective accomplishments have been substantial. Since the beginning of the Anacostia restoration effort, over 750 restoration projects have been identified to correct existing environmental problems and enhance overall ecosystem quality. Of this total, approximately one-third of the projects have been completed, and the remainders are in the process of being completed. A sampling of these projects, includes the Kenilworth Marsh and Kingman Lake wetland restoration projects in the District of Columbia, Anacostia Site 11 wetland restoration in Prince George's County, and dozens of stormwater retrofit (via LID and other techniques) and reforestation and trash reduction efforts in both the District of Columbia and Prince George's County portions of the tidal area. Several of these restoration projects have been the result of an effective partnership between local, state, regional and/or federal partners.

To get involved in protecting your Anacostia subwatershed contact Groundwork Anacostia.