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The Northwest Branch Watershed 

The Northwest Branch, located in the eastern part of the County, is the largest of the County's three contributing watersheds to the Anacostia (Northwest Branch, Paint Branch, and Little Paint Branch). Land uses differ greatly from the headwaters downstream to where the Northwest Branch flows into Prince George's County. Different development patterns have shaped the watershed, affecting the stream system to different degrees. Tributaries in the upper part of the watershed, particularly the headwaters, support the few remaining streams with excellent and good conditions in the Northwest Branch watershed.

The fish community found in Northwest Branch includes rosyside dace, northern hogsuckers, and five species of shiners. Although the same species can be found throughout the watershed, the community composition varies dramatically in response to habitat, flow, and pollutant stressors.

In the upper reaches, low density land uses are predominant and the landscape is in a transition from formerly widespread agricultural land uses to a more suburban landscape. The streams in this area are also in a transition, from carrying sediment loads and nutrients associated with past farming activities, to a watershed condition that includes less widespread land disturbance, but higher imperviousness. As this area develops and the imperviousness increases, today's environmental standards will provide forested buffers, floodplain and wetland protection, and management of stormwater runoff. However, even with application of modern stormwater controls, some changes in watershed hydrology are inevitable.

The middle section of the watershed contains a mix of moderate to higher density land uses along with large areas of forested parkland. Inadequate stream buffers on the tributaries and altered hydrology are common in this section. More of this area developed with stormwater controls than in the lower reaches; however, in many areas the stormwater management technologies used are not as effective as methods used today. Bel Pre Creek contains many such older controls, and is a focus of efforts underway to identify areas for improvements in runoff controls and stream channel restoration. The Rolling Stone tributary is the site of a relatively new stormwater retrofit project that has been successful in improving runoff controls in a previously developed area, modifying and updating structure performance and enhancing pond appearance.

The lower reaches of Northwest Branch contain older and more concentrated development, where communities developed long before requirements for stream valley protection or stormwater management. The hydrology in these areas has been significantly altered and the stream condition is generally poor or fair. However, also to be found in this part of the watershed is a stream section described as "the most scenic and rugged section of the Anacostia watershed". This is the beginning of the torrent and gorge section of the Northwest Branch that begins just below Route 29. This is a transitional area where the Northwest Branch leaves the Piedmont and passes through the fall line before entering the slower reaches of the Coastal Plain. This area contributed significantly to the state of Maryland identifying the Anacostia as a state "Scenic and Wild River" in 1984, under the Maryland Scenic and Wild Rivers Act.

Northwest Branch Stream Condition, Habitat Conditions and Management Category Designation

GOOD (Preliminary)
GOOD (Preliminary)
Problems with bank stability, sediment deposition and embeddedness are causing habitat impairment.


Watershed Protection Area - remedial

GOOD
GOOD
Sediment deposition and bank erosion adversely affecting habitat.
The Sandy Spring for which the area is named is located in this subwatershed.

Watershed Protection Area - remedial level

EXCELLENT
GOOD
Tributary is very shallow, limiting fish habitat, but has excellent benthic habitat. Some sediment deposition and bank erosion is occurring due to highly erodible soils.






Watershed Protection Area - special and remedial

EXCELLENT
GOOD Overall
Bank stability and sediment deposition problems observed.
Impacts related to previous agricultural use have created areas of channel instability which may make this tributary more sensitive to changes in hydrology.

Watershed Protection Area - special and remedial

GOOD
GOOD Overall
Bank stability, sediment deposition and embeddedness problems observed. Inadequate riparian buffer is limiting factor.




Watershed Protection Area - remedial

FAIR (Preliminary)
GOOD (Preliminary)
Problems with bank stability, sediment deposition and embeddedness are causing habitat impairment.


Watershed Restoration Area

GOOD
FAIR Overall

Fish habitat poor
Tributary contains a highly erodible sand substrate which affects all habitat parameters, particularly fish habitat. Benthic community is rated excellent




Watershed Protection Area - remedial Level

EXCELLENT
GOOD
Condition is on margin of good rating - problems include embeddedness, sed. deposition, and bank stability. Substrate is sandy and unstable.




Watershed Protection Area - special

POOR (preliminary)
GOOD (Preliminary)
Problems with bank stability, sediment deposition and embeddedness are causing habitat impairment.


Watershed Restoration Area

Upstream pond is influencing aquatic community.
Section between Brookside Nature Center and Kemp Mill Rd. in good condition.

Watershed Restoration Area

Watershed Restoration Area

Urban Stream Management Area

Watershed Restoration Area

The Northwest Branch Watershed Management Categories

A study is currently underway as part of the Anacostia Restoration Project, Phase II to examine opportunities throughout Northwest Branch for stormwater retrofit and stream restoration projects. This study is being conducted cooperatively by the MCDEP, M-NCPPC and the Army Corps of Engineers Baltimore District. A comprehensive watershed restoration action plan will result from this study. The management strategy outlined below is generally consistent with preliminary assessments in the study. It will be refined as the study progresses.

Watershed Protection Areas

These areas include the Lower Left Fork of the Upper Mainstem, the Sandy Spring tributary, the Upper Mainstem, Old Orchard tributary, Bryants Nursery tributary, Batchellor's Forest tributary, and the Rolling Stone tributary.

Special level of protection

Three subwatersheds with excellent stream conditions are placed in this category - Old Orchard tributary, Bryants Nursery tributary and Upper Mainstem. Due to existing and planned land uses, these three subwatersheds are not "preserved" in such a way that conditions are expected to remain excellent without some level of management to protect the resource from anticipated. The level of new development anticipated will increase imperviousness requiring special management tools to ensure that the stream conditions remain in the excellent range. Despite relatively low existing levels of imperviousness, these areas are experiencing erosion and stream bank instability problems that are believed to be associated with past clearing activities and land uses, as well as the erodibility of the soils. Bank instability and sediment deposition problems are pronounced in the Old Orchard tributary and Bryants Nursery tributary, and these two subwatersheds are identified as needing remedial protection tools as well as a special level of protection.

• Continue current efforts to closely monitor and apply state of the art BMPs to new development projects.

• Develop and implement targeted public education program for residents, businesses and developers about the high quality stream resources and special subwatershed management needs.

Remedial level of protection

Remedial protection tools are recommended for much of the headwaters of Northwest Branch, including Batchellors Forest tributary, the Lower Left Fork, Sandy Spring tributary, Old Orchard tributary, Bryants Nursery tributary, and Upper Main B, NWBr GC/Norwood tributary, and Rolling Stone tributary. The stream channels in these areas of the upper reaches of Northwest Branch, despite excellent and good biological community conditions, have been destabilized by past erosion and accelerated downcutting associated with land clearing activities without adequate best management practices, particularly the use of forested buffers. Many areas in these headwaters also have erodible soils that tend to make channels more susceptible to accelerated downcutting. These areas that have a combination of erodible soils and poor or marginal bank stability will benefit greatly from remedial efforts to re-stabilize channel morphology and facilitate the system's return to a stable condition.

• Identify and implement stream restoration and habitat improvement projects in conjunction with the Northwest Branch Watershed restoration effort and Action Plan currently underway.
• Provide targeted public education for residents, businesses and developers about the subwatershed resources and stewardship opportunities.

Watershed Restoration Areas

The Northwest Branch mainstem and tributaries from the Northwest Branch Golf Course downstream are designated restoration areas, with the exception of the the Rolling Stone tributary. In much of the area within this category, imperviousness levels are already high and are not expected to increase greatly. Highly impervious land uses occur throughout much of the lower watershed and stream conditions have been widely affected by uncontrolled runoff. Several of these subwatershed, particularly Bel Pre Creek have stormwater management controls which predate our current methods and therefore are frequently less effective.

The Lockridge Dr. subwatershed has been extensively piped and channelized, and where the stream re-emerges into a natural channel, extreme downcutting has occurred, in places to the bedrock. No opportunities exist to substantively improve the quantity of stormwater runoff in this subwatershed, however, small incremental improvements may be achieved through voluntary actions to slow runoff from yards and roof-drains. A stream restoration project is planned to stabilize the channel and guard against continued degradation. Efforts targeted at controlling non-point source pollutants, such as nutrient control from yards and pet waste, and small voluntary improvements to control yard runoff will help to improve runoff quality from this subwatershed.

• Identify and implement stormwater retrofit, stream restoration and habitat improvement projects in conjunction with the Northwest Branch watershed restoration effort currently underway.
• Develop Northwest Branch Watershed Restoration Action Plan to implement stormwater retrofit and stream restoration projects and comprehensive watershed education and stewardship program.

Maps

Land Cover
Impervious Area
Stream Condition
Management Categories

Land Cover Graph

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