Final TMDLs Approved by EPA: Rock Creek

The Rock Creek watershed comprises approximately 76 square miles (48,640 acres), with approximately 80% of the drainage within Montgomery County, Maryland and the remaining 20% within Washington, D.C. Rock Creek begins flowing at Laytonsville, Maryland, and continues to flow through Montgomery County, through Washington, D.C. until it reaches the Potomac River.  The North Branch of Rock Creek starts flowing at Mount Zion, Maryland and discharges to Rock Creek in Rockville, Maryland.  There are two surface impoundments located in the Rock Creek watershed: Needwood Lake and Lake Bernard Frank.

The Maryland Department of the Environment (MDE) has identified the non-tidal portion of Rock Creek, Use I – Water Contact Recreation and Protection of Aquatic Life; Use III – Natural Trout Waters; and Use IV – Recreational Trout Waters [Code of Maryland Regulations (COMAR)] in the State’s 303(d) as impaired by nutrients (1996), sediments (1996), fecal bacteria  (2002), and impacts to biological communities (2002).  Water Quality Analyses for eutrophication in Needwood Lake and Lake Bernard Frank, located in the Rock Creek watershed, were approved by EPA in 2003.  The District of Columbia  (D.C.) has established a fecal bacteria TMDL for the portion of Rock Creek within D.C.'s boundaries.  The document, available below, establishes a TMDL of fecal bacteria in the non-tidal portions of Rock Creek to allow for the attainment of beneficial use designation, primary contact recreation.  The listings for nutrients, sediments, and impacts to biological communities will be addressed separately at a future date. 

Total Maximum Daily Loads of Fecal Bacteria for the Non-Tidal Rock Creek Basin in Montgomery County, Maryland

(Approved on July 30, 2007)

EPA's Decision Letter EPA's Decision Letter
Main Report TMDL_rockcreek_fc.pdf (2437KB)

Comment Response Document

CRD_rockcreek_fc.pdf (24KB)


Contact Information

Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3818.