The highly urbanized Anacostia River watershed covers 176 square miles in the District of Columbia and Maryland. Only 17 percent of the watershed lies within the District; much of this drainage is controlled by storm sewers or combined (storm and sanitary) sewers. Combined sewer overflows (CSOs) drain approximately 11 square miles of the basin in the District and 17 CSO outfalls drain directly into the tidal Anacostia River.
The Anacostia River was included in the District’s 1998 Section 303(d) list of impaired waters for oil and grease because of observed sheens of oil on Hickey Run, a tributary to the Anacostia River. Oil from Hickey Run would enter the Anacostia River and cause exceedances of the criteria (10 mg/L).
The following total maximum daily load (TMDL) for oil and grease in the Anacostia River was approved on October 31, 2003.
Below is the final TMDL for oil and grease in the Anacostia River watershed in addition to decision rationale from EPA.