Rock Creek flows through Montgomery County, Maryland, and the northwest portion of Washington, DC, to join with the Potomac River. The watershed is 76.5 square miles with approximately 21 percent (or 15.9 square miles) in the District and 79 percent in Maryland. Rock Creek and its tributaries were listed in 1998 for elevated levels of organics and metals in fish tissue and sediment in the Anacostia River. Subsequent water quality data indicated some level of organic impairment. The total maximum daily loads (TMDLs) were approved for Rock Creek parameters identified in the table below on February 27, 2004.
The TMDLs were challenged in Friends of the Earth v. EPA 446 F.3d 140 (D.C. Cir. 2006) because the loads were not expressed in daily loads. Following the case, a settlement agreement was reached between the US Environmental Protection Agency (EPA) and Anacostia Riverkeeper, Friends of the Earth, and Potomac Riverkeeper (Case No.: 1:09-cv-00098-JDB of January 15, 2009). To meet the settlement requirements, EPA will revise the applicable TMDLs to express daily loads. DDOE is working with EPA to collect/analyze data and revise the TMDLs for toxic parameters. The table below lists the TMDL water bodies and pollutant pair with the current impairment status in the District’s 2014 Integrated Report. In the table below, those water body/pollutant pairs categorized in 4a will be revised. However, in several water bodies, recent data was insufficient to support an impairment determination, or the samples met water quality standards and therefore the water body/pollutant was removed from the impaired list for a particular pollutant.
For more information, please see the District’s 2014 Integrated Report.
The 2004 final approved TMDL documents for metals and organics in Rock Creek tributaries are included below. The revised documents will be posted when available.