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Rock Creek Watershed

The Rock Creek Watershed includes two major subwatersheds:  the Upper Rock Creek and the Lower Rock Creek.   The Upper Rock Creek watershed contains many miles of small headwater streams unlike Lower Rock Creek,  where prior development piped many headwater areas.

Watershed restoration efforts in Montgomery County are making progress in bringing positive changes throughout this watershed. These efforts include a watershed restoration feasibility study (PDF, 994KB) conducted by the Department of Environmental Protection (DEP) as well as a similar study by the City of Rockville, and efforts by the National Naval Medical Center to restore Stoney Creek, a tributary on this federal property. The DEP has also completed a watershed implementation plan which lays out the strategy needed to meet the State's water quality standards for the watershed.


A Journey Through the Upper Rock Creek Subwatershed

The rolling fields and farmland in the Upper Rock Creek subwatershed have changed over the past 40 years as homes and businesses have replaced former dairy farms and corn fields. People can still remember when brown trout were regularly caught in the clear running waters of Rock Creek. Today, brown trout still survive in these streams, but they are becoming increasingly harder to find.

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 Rd.) are still relatively undeveloped. The County has acquired protective stream valley parkland buffers along the upper Rock Creek mainstems 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 park was one of the first County parks to have stream resource protection goals and objectives included in the master plan text.

Image of Crabbs Branch

Land uses in the drainage area from Fieldcrest Rd. downstream to Muncaster Rd. consist of newly developing large-lot residential subdivisions, commercial lots along Route 124, and existing low- to medium-density residences. Between Muncaster Rd. and Muncaster Mill Rd., 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.

  • Image of Sandy BranchMill Creek has a poor to fair resource condition, reflecting the dense development in its headwaters that was built with little or no stormwater 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.         

Watershed Protection Areas: Special protection tools are recommended for many of the headwater areas to protect the sensitive resources in these streams where projections indivate further development might occur.


A Journey Through the Lower Rock Creek Subwatershed

Lower Rock Creek consists of the Rock Creek subwatersheds below Norbeck Rd. (Route 28). The Creek narrows here and the stream flows south through Montgomery County and the District of Columbia, eventually discharging into the Potomac River. Lower Rock Creek was one of the earliest areas of the County to experience development pressure as residents of the District made their summer homes along the Rock Creek corridor.

Over the years, the subwatershed as a whole, and the lower sections in particular, have undergone rapid change as the push for housing and jobs has moved from the city to the suburbs. Today, most of Lower Rock Creek is a heavily urbanized, densely populated area that developed many years before there were requirements for managing stormwater runoff.


Rock Creek Park

The Lower Rock Creek watershed contains one of the first County stream valley park systems. This park system directly connects to the Rock Creek National Park in the District of Columbia. One of the region's most heavily used and valued recreation corridors, the Rock Creek hiker-biker trail system, runs along the stream valley, linking the Montgomery County suburbs from Lake Needwood all the way down to the National Zoo and beyond. This stream valley park system also provides a protective buffer along the stream, preserving vernal pools and wetlands in the floodplain.

Vernal pools near the County line still support a community of amphibians, which have all but disappeared in other urban stream valley areas. Spotted salamanders return to the same vernal pools that have supported populations of this long-lived (over 20 years) amphibian for generations. Other amphibian species, such as American toad, wood frog, and spring peeper, are also locally abundant in this urbanized corridor.

Image of South Lawn Watershed

The Health of Lower Rock Creek

The overall resource condition for Lower Rock Creek is fair to poor. Although conditions immediately upstream (in the Upper Rock Creek watershed) are rated as good, resource conditions below Route 28 rapidly change to poor. Resource conditions improve to a fair level from the vicinity of Turkey Branch downstream to the vicinity of Kensington Heights, but degrade back to a poor level almost to the Montgomery County line.

Despite the extensive impacts on Lower Rock Creek from intensive development and urban runoff conditions, the mainstem still supports a warm-water fish community.

  • Large redbreast sunfish can be found in many of the scoured-out pools.
  • Large hellgramites have also been found in some of the riffles and shallow runs.

Rock Creek historically supported an abundant anadromous fish community (fish that live in saltwater and spawn in freshwater). Efforts are under way by the National Park Service to study options and implement efforts within the District of Columbia to remove fish blockages in Rock Creek Park.


How Can I Help Protect the Rock Creek Watershed?

Individuals interested in helping to protect the health of Rock Creek can contact the Rock Creek Conservancy. This organization of local citizens prides itself in keeping the streams that flow into the Rock Creek Valley healthy and alive for all to enjoy.


Map of Montgomery County with the Rock Creek watershed highlighted