At first glance, the term watershed might sound like complicated jargon, but don’t worry, it isn’t. A watershed is simply all of the land area that drains into a particular body of water, such as a creek or river. What happens in the watershed can affect that body of water.
The Rock Creek Watershed is the land area that drains into Rock Creek or one of its tributaries. The watershed includes 77.4 square miles of land. The main stem of the creek is 33 miles long, and it has over 30 tributaries. The creek originates in springs near Laytonsville in Montgomery County, Maryland, and that's where the watershed begins. The creek flows south through the District of Columbia and empties into the Potomac River. Click on the Rock Creek Watershed map to view a larger image.
When people think of Rock Creek, they usually focus on the small bit of the watershed located inside DC's Rock Creek Park. Yet public and private property in Montgomery County makes up more than 60 square miles of the watershed. The watershed undergoes changes in land use as you move south through upper Montgomery County into lower Montgomery County and into Washington, DC.
The Montgomery County portion of the watershed is divided into upper and lower sections, with the divide occurring at Norbeck Road/Md. 28. The upper section, which encompasses 29.5-square miles, consists of Maryland-National Capital Park and Planning Commission (MNCPPC) parkland (23%) and agricultural land (10.5 percent, mostly privately owned), with the rest in various other uses. The most sensitive lands in this area are protected parkland properties. Lake Needwood and Lake Frank are both in this section of the watershed. As you go further south toward Norbeck Road development of housing and commercial areas gets denser. Water quality in this section of the watershed is typically rated as good.
In lower Montgomery County, the watershed narrows. This section of the watershed is 31.5-square miles in area and highly urbanized. Dense development and an increased population contribute to decrease in water quality in this section of the Rock Creek due to runoff and other factors. Resource conditions in this section of the watershed are typically rated as fair to poor as a result.
The Montgomery County Department of Environmental Protection has a Watershed Finder map. You can see which stream is connected to any address and learn about its water quality.
Rock Creek flows into the District near Boundary Bridge in Chevy Chase. The DC section of the watershed is 16.8-square miles in area and contains even denser development. Within the District, the watershed includes both the protected Natural Park Service park property and the surrounding urban environment. Dense development and increased population contribute to runoff and other problems detrimental to the health of the creek and watershed as a whole.
The Rock Creek Watershed finally ends where Rock Creek flows into the Potomac River near Thompson's Boathouse, the Watergate complex and the Kennedy Center for the Performing Arts. The last quarter mile of Rock Creek is tidally influenced. The Potomac flows on into Chesapeake Bay.
Think of Rock Creek, the Potomac, and the Chesapeake Bay watersheds as a series of Russian nesting dolls…. Along with Rock Creek, other streams and rivers flow into the Potomac. Along with the Potomac, other rivers flow into the Chesapeake Bay. By taking steps to protect Rock Creek you’re also contributing to the health of the Chesapeake Bay.