Montgomery County Watershed-Specific Restoration Plans: Anacostia Watershed

The Anacostia River Watershed spans areas of Montgomery County, Prince George's County, and Washington, DC., and has been the focus of inter-jurisdictional watershed management and restoration since the early 1980's. It is a major tributary to the Potomac River. Four subwatersheds along the eastern boundary of Montgomery County provide drainage to the Anacostia: Northwest Branch, Paint Branch, Little Paint Branch, and Sligo Creek. The drainage within Montgomery County is approximately 61 square miles, and accounts for roughly one third of the total drainage area to the Anacostia River. Stream conditions vary from the good conditions of the Upper Paint Branch (a nationally recognized urban trout stream) to the poor conditions found within Sligo Creek (where restoration has been ongoing for over 15 years). Many areas of the Anacostia watershed contain residential areas that were built before modern stormwater controls were required by the State. This has resulted in deterioration of the stream channel habitat, particularly in the more southern portions of the watershed. In the northern reaches, particularly in Northwest Branch and Upper Paint Branch, there are some tributaries which still have good stream resource conditions and targeted for protection.

Northwest Branch

The Northwest Branch of the Anacostia River originates south and east of Olney, MD near the intersection of Route 108 and Georgia Avenue, and flows south approximately 15 miles before passing into Prince Georges County, where it is joined by several other major tributaries to form the Anacostia River. Above Ednor Road, there is much low density development, and streams are undergoing a transition from widespread historic agricultural use to higher impervious land uses. Newer development in this area must provide stream buffers and modern stormwater management techniques, but some changes in watershed hydrology are inevitable. Below Ednor Road, the middle section of the subwatershed contains a mix of moderate to higher density housing interspersed with large areas of parkland. Some stormwater controls are in place, but they are less effective than current technology. Altered hydrology is common in this section, and many of the tributaries have insufficient stream buffers. Below Bonifant Road, the downstream portion of Northwest Branch is an older urban subwatershed. It is highly developed and densely populated in many areas, with very little stream valley protection or stormwater management. As a result, stream conditions have been significantly altered.

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Sligo Creek

The Sligo Creek headwaters are located in the Wheaton area, north of the intersection of Georgia Avenue and University Avenue. Sligo Creek flows southeast approximately eight miles before passing into Prince Georges County, where it joins the Northwest Branch of the Anacostia River. It is one of the County's most urbanized areas, containing high density residential and commercial areas such as Wheaton Triangle, Wheaton Central Business District, parts of Silver Spring, and Takoma Park. This older development was established before today's modern stormwater structures and environmental buffers were required. There are many areas where tributaries were paved over and piped into storm drains and where the larger stream channels have been heavily armored to resist erosion. Although this does provide increased bank stability, it reduces available instream habitat. Areas that have not been armored suffer from varying degrees of erosion due to unmitigated stormflows.

This subwatershed was the first targeted for Anacostia restoration efforts within the County. Since the early 1990's, these have included new runoff controls, improvements to the sanitary sewers, and stream channel restoration. This has lead to notable increases in stormwater management and improving instream habitat stability. There have also been multiple efforts to reintroduce native fish in the upper mainstem of Sligo Creek, with the number of native fish species increasing from only two species in 1988 to 11 in 1998.

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Paint Branch

The Paint Branch subwatershed begins near Spencerville, MD, just to the south and east of the intersection of Spencerville Road and New Hampshire Avenue. Paint Branch flows south for approximately nine miles before entering Prince Georges County, and then joins Little Paint and several other major tributaries to form the Northeast Branch of the Anacostia River. Paint Branch is unique in that it provides a coldwater fishery and wild brown trout population close to the Nation's capital. The Gum Springs and Good Hope tributaries provide spawning/nursery areas and cold clean baseflow for young trout, while the Right Fork and lower portions of the Left Fork provide good adult brown trout habitat. The mainstem supports adult trout populations as far downstream as I-495. Land use in the upper portion of Paint Branch is primarily older areas of low and medium density residential housing, with some commercial and agricultural activities. Development occurred primarily before requirements for stormwater controls were put in place. There is some stream impairment. There has been a continuing effort to improve the stream through restoration projects and the purchase of large areas of forested parkland to provide protection to the riparian areas.

In 1995, to maintain this unique County resource, the upper portion of the watershed was designated a SPA with an 8% impervious cap on new development. The lower portions of the Paint Branch mainstem and its tributaries have been impaired by runoff from the high density land development that took place without adequate stormwater management. Forest cover in the lower Paint Branch is largely confined to the stream valleys, but does provide a cooling effect on the stream and keeps water temperatures within the range needed to support the adult brown trout found here.

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Little Paint Branch

Little Paint Branch is located in the easternmost portion of Montgomery County. It is unique in that it is a transition area between the Piedmont ecoregion and the Coastal Plain ecoregion. The headwaters originate east of Spencerville, near the intersection of Route 29 and Spencerville Road, and the stream flows south for approximately three miles before entering Prince Georges County, where it joins Paint Branch.. Little Paint Branch is transected by the Rt. 29 corridor, which contains many of the County's important industrial and commercial complexes. Many regional stormwater controls have been installed in the upper portions of Little Paint to mitigate the effects from high density residential and commercial land uses. The lower portions of the subwatershed were developed prior to requirements for stormwater control, leading to degraded conditions. High densities in this part of the subwatershed and lack of available public land make retrofitting these areas difficult.

Anacostia Summary Document and Maps (PDF, 6 pp, 4.3Mb)

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Anacostia Watershed Restoration Plan

The US Army Corps of Engineers, Baltimore District, working with partners at the state and local levels, began work on a restoration plan for the watershed in 2007. The goal of the planning effort is to produce a systematic 10-year plan for environmental and ecological restoration within the Anacostia River watershed. The plan is expected to be completed by the end of 2009. More information can be found at the Anacostia Watershed Restoration Partnership web site.

Montgomery County Draft Anacostia Watershed Implementation Plan (PDF, 52 pp, 2.63Mb)

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