Rock Creek (Potomac River)
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Rock Creek Potomac River
Rock Creek
Rock Creek, Washington, D.C.
CountyMontgomery County, Maryland
CitiesRockville, Maryland
Washington, D.C.
Physical characteristics
 • locationLaytonsville, Maryland
 • coordinates39°11?56?N 77°08?20?W / 39.1990012°N 77.1388044°W / 39.1990012; -77.1388044
 • elevation560 feet (170 m)
 • location
Potomac River
 • coordinates
38°53?58?N 77°03?26?W / 38.899556°N 77.0572°W / 38.899556; -77.0572Coordinates: 38°53?58?N 77°03?26?W / 38.899556°N 77.0572°W / 38.899556; -77.0572
 • elevation
0 feet (0 m)
Length32.6 miles (52.5 km)
Basin size76.5 square miles (198 km2)
 • average63.7 cu ft/s (1.80 m3/s)
Basin features
LandmarksRock Creek Park
WaterbodiesLake Needwood

Rock Creek is a free-flowing tributary of the Potomac River that empties into the Atlantic Ocean via the Chesapeake Bay. The 32.6-mile (52.5 km) creek[1]drains about 76.5 square miles (198 km2). Its final quarter-mile (400 m) is affected by tides.[2]


The creek rises from a spring near Laytonsville in Montgomery County, in the U.S. state of Maryland, and joins the Potomac near Georgetown and the Watergate complex in Washington, D.C. It enters Rock Creek Regional Park in Maryland's Derwood-Rockville area and flows southward to the D.C. boundary.[3] About 9 miles (14 km) of the creek flow through Rock Creek Park in Washington, where it is fed by several small creeks (Piney Branch, Pinehurst Branch, Broad Branch, Soapstone Branch, and Luzon Branch) and numerous storm sewers.

The Chesapeake and Ohio Canal joins Rock Creek in Georgetown; the creek's mouth is the canal's eastern terminus. Just below this confluence, the Canal Company in 1831 completed a mole, causeway, and waste weir. This area, which the company dubbed "Rock Creek Basin",[4]:251 silted up and was dredged several times for the Canal's use.[4]:22 The creek (and the canal) empty into the Potomac River at the Tidewater Lock.

The Maryland portion of the watershed comprises the second-largest watershed in Montgomery County, about 60 sq mi (160 km2). About 21 percent of the creek's watershed is in Washington. Total land usage in the watershed is 896 acres (3.63 km2) of wetlands or water, 22,272 acres (90.13 km2) of residential and commercial areas, 15,488 acres (62.68 km2) of forest or grasslands, and 10,304 acres (41.70 km2) of agricultural areas. The creek has a fairly steep gradient, with rapid changes in elevation. The man-made Lake Needwood is located on the creek, north of Rockville.

The conditions at the Rock Creek are monitored by the USGS.[5]

Water quality and restoration

Rock Creek in Chevy Chase, Maryland. The stream bank shows downcutting (vertical erosion) due to stormwater runoff.

In Maryland, most of the northern Rock Creek watershed has good to excellent water quality, according to studies conducted by the county government. In 2004, to preserve water quality in partially developed areas, the county imposed restrictions on development (i.e., designation of "Special Protection Areas") in parts of this sub-watershed.[6] The southern portion of the Maryland watershed is highly urbanized. Most of this portion of the creek and its tributaries have poor water quality.[7] As of 2018 the county has completed several stream restoration projects throughout the watershed, and has additional projects planned or under construction.[8][9]

The D.C. segment of Rock Creek also has poor water quality. In addition to typical urban stormwater pollution problems such as runoff from streets and other impervious surfaces, the creek has high bacteria levels due to combined sewer overflows (CSOs).[10] The D.C. government, which has a stormwater discharge permit from the United States Environmental Protection Agency, is improving its stormwater management to raise water quality in Rock Creek.[11] In 2009, the District of Columbia Water and Sewer Authority began a planned two-year effort to replace portions of the combined sewer with separate storm sewers, and so eliminate CSO-related problems in the creek.[12]

Fish species observed in Rock Creek and its tributaries include eastern blacknose dace, bluntnose minnow, yellow bullhead, satinfin shiner, swallowtail shiner, longnose dace, and American eel.[13]

Restoration projects

Boulder step pools were installed in a Rock Creek Park stream segment. The pools raise the water level and allow fish to swim over a partially-submerged sewer pipe which crosses the creek.

In 2006, the National Park Service finished a project to remove or bypass eight fish barriers in the creek by adding a fish ladder to bypass the 1905 Peirce Mill Dam, modifying historic fords, and removing abandoned sewage lines and fords. The effort is designed to restore American shad, river herring, and other migratory fish to the creek and their historic upriver spawning grounds.[14] An estimated two million fish migrate up the creek each year.[]

The D.C. government completed a restoration project on the Milkhouse Run and Bingham Run tributaries in 2013. As of 2014, ongoing restoration projects in the watershed include the Broad Branch and Klingle Run tributaries.[15][16]


(Listed in order from the mouth upstream)

In D.C.
  • Dumbarton Oaks
  • Normanstone Creek
  • Klingle Valley Creek (also called Klingle Creek, Klingle Run)
  • Piney Branch
  • Melvin Hazen Valley Branch
  • Broad Branch
    • Soapstone Branch
  • Luzon Branch
  • Milkhouse Run
  • Bingham Run
  • Pinehurst Branch
  • Fenwick Branch
    • Portal Branch
In Maryland
  • Donnybrook Tributary
  • Coquelin Run
  • Capitol View Tributary
  • Kensington Heights Branch
  • Stoney Creek
  • Alta Vista Tributary (formerly Bethesda Run)
  • Luxmanor Branch
  • Stoneybrook Tributary
  • Josephs Branch
  • Turkey Branch
  • Sycamore Creek
  • Croydon Park Tributary
  • Southlawn Branch
  • Williamsburg Run
  • North Branch (Lake Bernard Frank)
  • Lake Needwood (in-line on Rock Creek)
  • Crabbs Branch
  • Mill Creek
  • Pope Farm Branch
  • Airpark Road Branch

See also


  1. ^ U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed August 15, 2011
  2. ^ U.S. Geological Survey, Baltimore, MD, 2002. Water Quality, Sediment Quality, and Stream-Channel Classification of Rock Creek, Washington, D.C., 1999-2000. Anita L. Anderson et al. Water-Resources Investigations Report 02-4067.
  3. ^ "Rock Creek Regional Park". Silver Spring, MD: Montgomery County Department of Parks. Retrieved .
  4. ^ a b Unrau, Harlan D. (August 2007) [Authored/unpublished 1976]. Gray, Karen M. (ed.). Historic Resource Study: Chesapeake & Ohio Canal (PDF) (Report). Hagerstown, MD: US Department of the Interior, National Park Service.
  5. ^ "ROCK CREEK AT SHERRILL DRIVE WASHINGTON, DC". USGS Water Data for the Nation. 1 October 1990. Retrieved 2020.
  6. ^ Montgomery County Department of Environmental Protection (MCDEP). Rockville, MD. Special Protection Area Program Annual Report 2005. January 2007.
  7. ^ MCDEP. Rock Creek Watershed Restoration Action Plan, July 2001.
  8. ^ Parker, Pam (2014-10-14). "Montgomery County, MD: The Municipal Separate Storm Sewer System Permit" (PDF). MCDEP.
  9. ^ "Restoration Projects". Watershed Restoration. MCDEP. Retrieved .
  10. ^ U.S. Environmental Protection Agency. Philadelphia, PA. February 27, 2004. Decision Rationale: Total Maximum Daily Loads for Fecal Coliform Bacteria in Rock Creek.
  11. ^ District of Columbia. Department of the Environment. August 17, 2007. 2007 Implementation Plan: District of Columbia NPDES Permit No. DC0000221 Municipal Separate Storm Sewer System. Archived 2008-02-27 at the Wayback Machine
  12. ^ District of Columbia Water and Sewer Authority (2009). "Rock Creek Sewer Separation - 2009." Fact Sheet.
  13. ^ National Park Service (NPS), Washington, D.C. (June 2012; rev. June 2015). "National Capital Region Network Resource Brief: Fish, Rock Creek Park."
  14. ^ NPS. "Removing Barriers to Restore Fish Populations." The Current (newsletter). Vol. 2, No. 3. Fall 2007.
  15. ^ District of Columbia, Dept. of the Environment. "Habitat Restoration." Accessed 2014-03-29.
  16. ^ District of Columbia, Dept. of Transportation (2014-01-16). "Klingle Valley Trail Public Meeting."

External links

  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.



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