The Upper Rock Creek watershed is located in the central portion of the county and is the first major Potomac tributary west of the Anacostia River drainage. Upper Rock Creek is bounded by Dorsey Road (near Laytonsville) to the north, Olney-Laytonsville Road (Route 108) to the east, Route 28 to the south, and the Gaithersburg-Laytonsville Road (Route 124) to the west.

Rock Creek begins as a small spring emerging from an old spring house in the Laytonsville area. The upper reaches of the watershed (above Fieldcrest Road) are still relatively undeveloped. The County has acquired protective stream valley park land buffers along the upper Rock Creek main stems to help maintain the good to excellent resource conditions currently found here. Relatively unimpaired, this portion of Rock Creek supports several of the County's reference stream reaches. Passing under Fieldcrest Road, Rock Creek soon joins another main headwater tributary just above the Agricultural History Farm Park. The Agricultural History Farm Park was one of the first County parks to be master planned with stream resource protection goals and objectives included in the plan text.

Land uses in the drainage area from Fieldcrest Road downstream to Muncaster Road consist of newly developing large lot residential subdivisions, commercial uses along Route 124, and existing low to medium density residences. Under State law, many of the existing large lot developments have not had to provide stormwater quantity controls, although some have had to provide water quality controls for runoff. Some subdivisions now being constructed will be required to provide full quantity and quality runoff controls. Between Muncaster Road and Muncaster Mill Road, Rock Creek increases in size as its drainage area enlarges. Medium density residential development predominates, although there are still areas of large lot developments in the drainage. The stream valley in this area is in succession from farm fields to young forest.

Mill Creek currently has a poor to fair resource condition reflecting the density of development in its headwaters that was built with little or no SWM controls. This area has a combination of townhouses, single family homes, and apartments. The Crabbs Branch subwatershed has a highly impervious commercial area in its headwaters and the Crabbs Branch Regional Stormwater Pond was constructed to control the runoff from these facilities. The Southlawn Branch has an old industrial area in its headwaters that includes cement mixing facilities and sand and gravel operators. There are few stormwater runoff controls in this area. DEP monitoring at the outfall from the Southlawn Branch industrial area indicated an alkaline pH problem in the discharge. DEP is working with different cement mixing facility owners to improve on-site BMPs to reduce the pollutant discharges from these properties. An old landfill (Gude) in this subwatershed currently has a methane recovery system in place and BMP's to provide control of the runoff from the site. Lake Needwood is eutrophic, and downstream of the lake the water temperature and quality are noticeably impaired.

Upper Rock Creek Stream Condition, Habitat Conditions, and Management Category Designation

Upper Rock Creek Watershed Management Categories

The Upper Rock Creek watershed contains many subwatersheds supporting excellent stream conditions. Some of these areas are fragmented by stream sections showing signs of impairment, and the overall resiliency of this high quality headwater system is somewhat compromised by this pattern. Measures to improve and stabilize impacted areas will greatly benefit the overall function of this system. Many of the areas currently supporting "good" stream conditions may be capable of supporting an excellent community through targeted efforts to improve, stabilize and protect areas showing signs of stress. Many of these areas are projected to have only modest increases in imperviousness. Planning efforts in the Upper Rock Creek watershed have emphasized preserving the health of this stream system, as well as protecting the valued recreational resources and maintaining the flood protection benefits provided by Lake Needwood. DEP is in the process of developing a watershed restoration action plan for addressing stormwater retrofit, stream restoration, and habitat improvements comprehensively throughout the watershed. The management approach outlined below will be updated as necessary to incorporate feasibility study results and watershed restoration action plan recommendations.

Watershed Preservation Areas

This category includes the Lower North Branch subwatershed. The low levels of existing and projected imperviousness in Lower North Branch should continue to preserve the excellent conditions found here, in combination with efforts to maintain and improve upstream conditions.

• Pursue efforts as part of a comprehensive watershed action plan to address upstream conditions.

Watershed Protection Areas

This designation includes all of the subwatersheds currently assessed as supporting excellent or good stream conditions, with the exception of Lower North Branch which is discussed above.

Special level of protection

Special protection tools are recommended for many of the headwater areas to protect the sensitive resources in these streams where projections of imperviousness indicate the highest levels of subwatershed land use change may occur.

• Target efforts to maintain and improve forested riparian buffer areas through various options (e.g. conservation easements, parkland acquisition and/or dedication, targeted off-site forest conservation, voluntary implementation by landowners, etc.)
• Develop and implement public education program residents, businesses and developers to increase awareness of stream resources and special management needs.
• Pursue imperviousness reduction strategies, targeted habitat improvements
• Identify habitat improvement opportunities through development of overall watershed restoration action plan.

Remedial level of protection

Middle North Branch A and B are identified for remedial levels of protection in order to address existing habitat impairment and other problems in these subwatersheds. Imperviousness is not projected to increase to over 10% in these areas, and the potential for restoring these areas to a level supporting excellent stream conditions may exist.

• Identify and pursue opportunities for stream restoration and habitat improvement projects as part of development of the overall watershed restoration action plan.

Regular level of protection

Three areas are identified for regular levels of protection, Crabbs Branch, Lake Frank and Lake Frank East. These subwatersheds contain good stream conditions which should continue to be protected by the application of standard environmental guidelines and regulations. Potential habitat improvement or structural improvements at the Crabbs Branch pond will be examined through the Rock Creek watershed feasibility study being conducted by DEP.

• Continue current practices.
• Identify and pursue opportunities for stream restoration and habitat improvement projects as part of development of the overall watershed restoration action plan.

Watershed Restoration Areas

All of the subwatersheds supporting fair or poor stream conditions are identified as watershed restoration areas, with the exception of Southlawn Branch.

• Identify and pursue opportunities for stream restoration and habitat improvement projects as part of development of the overall watershed feasibility study and restoration action plan.
• Increase public education and outreach efforts, including involving local citizens in Pipe Detectives and pollution prevention efforts.

Urban Watershed Management Area

Southlawn Branch is designated an urban watershed management area out of the need to address existing urban water quality impacts in this watershed as a first priority.

• Continue efforts to work with businesses in identifying pollution prevention measures to improve water quality conditions.
• Identify and pursue stormwater retrofit opportunities through the overall watershed feasibility study and restoration action plan.

Maps
Land Cover	Impervious Area	Stream Condition	Management Categories

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