Total Maximum Daily Loads of Nutrients/Biochemical Oxygen Demand for the Anacostia River Basin, Montgomery and Prince George�s Counties, Maryland and The District of Columbia

Final TMDLs Approved by EPA: Anacostia River

The Anacostia River watershed comprises a 173 square mile drainage area that includes highly urbanized areas in DC, old and newly developing suburban neighborhoods in the surrounding metropolitan area, croplands and pastures at the U.S. Department of Agriculture’s (USDA) Beltsville Agricultural Research Center (BARC), and forested parklands throughout the watershed.  The Anacostia and many of its tributaries cross interstate boundaries, with 145 square miles of the watershed (84%) lying in MD, and 28 square miles (16%) in DC.

The main channel of the Anacostia is 8.4 miles (13.5 kilometers) in length, extending from the confluence of its two largest tributaries, the Northwest Branch (NWB) and the Northeast Branch (NEB), in Bladensburg, MD, to the location where the Anacostia discharges into the Potomac River in DC.  The main channel of the Anacostia is an estuary with a variation in water level of approximately three feet over a tidal cycle.  Tidal influence extends into the lower reaches of the river’s tributaries to approximately the locations of the U.S. Geological Survey (USGS) gage stations 01649500 on the NEB and 01651800 on Watts Branch, and to the bridge at U.S. Route 1 (Rhode Island Avenue) on the NWB.  Approximately 70% of the watershed is drained by the two largest tributaries, the NWB and the NEB.  The other two major tributaries of the Anacostia, Lower Beaverdam Creek (LBC) and Watts Branch, drain highly urbanized areas in Prince George’s County and DC.

In Maryland, the Anacostia and its tributaries have been variously designated as Use I-P, II, III and IV waters [Code of Maryland Regulations (COMAR) 26.08.02.08 O].  These uses are defined as follows:  Use I-P – Water Contact Recreation, Protection of Aquatic Life and Public Drinking Supply; Use II: Tidal Waters: Support of Estuarine and Marine Aquatic Life and Shellfish Harvesting Use III – Natural Trout Waters; and Use IV – Recreational Trout Waters.  The Maryland Department of the Environment (MDE) has identified the Anacostia (MD basin number 02140205) on the State's 303(d) List as impaired by the following (listing years in parentheses): nutrients (1996); sediments (1996); fecal bacteria (2002); impacts to biological communities—non-tidal waters (2002); toxics: polychlorinated biphenyls (PCBs) and heptachlor epoxide—non-tidal waters (2002); trash/debris (2006); and PCBs in fish tissue in tidal waters (2006).  Fecal bacteria TMDLs for MD tidal and non-tidal areas of the Anacostia were established in 2006.  A watershed-wide TMDL for sediment/TSS, addressing the listings for those impairments to the Anacostia in their respective jurisdictions, was established jointly by DC and MD in 2007.  A multi-jurisdictional TMDL for PCBs in the tidal portions of the Potomac and Anacostia Rivers were established jointly by DC, MD and VA in 2007.  The listings for other impairments in tidal and non-tidal waters will be addressed separately at a future date.

The District of Columbia (DC) has classified the Anacostia for current and designated uses including category Class C: “Protection & Propagation of fish, shellfish and wildlife.”  [District of Columbia Municipal Regulations (DCMR), Chapter 11, Section 1101.2], DC’s 303(d) List divides the Anacostia within the District’s borders into two segments.  The lower Anacostia is identified as that portion of the river extending from the mouth of the river to the John Philip Sousa Bridge and Pennsylvania Avenue and the upper Anacostia from the bridge to the Maryland border.  The upper and lower segments of the Anacostia were listed on DC’s 1998 Section 303(d) List as impaired by biochemical oxygen demand (BOD), bacteria, organics, metals, total suspended solids (TSS), and oil and grease.  DC has previously developed TMDLs to address all of these impairments in its portion of the Anacostia; however, a 2006 court decision required the development of new BOD and TSS TMDLs for the Anacostia that include maximum daily load expressions in addition to longer-term (average annual, seasonal) loads.

The document available below establishes TMDLs for nutrients and BOD in the tidal and non-tidal portions of the Anacostia watershed in both MD and DC that will allow for the attainment of their respective designated uses.  The BOD TMDLs established herein replace the DC BOD TMDLs vacated by the DC Circuit Court. 

Total Maximum Daily Loads of Nutrients/Biochemical Oxygen Demand for the Anacostia River Basin, Montgomery and Prince George’s Counties, Maryland and The District of Columbia

(Approved on June 5, 2008)

EPA's Decision Letter EPA's Decision Letter
Main Report TMDL_anacostia_nutrients_BOD.pdf (2019KB)
Appendix A TMDL_anacostia_appendixA_nutrients_BOD.pdf (77KB)
Appendix B TMDL_anacostia_appendixB_nutrients_BOD.pdf (702KB)
Appendix C TMDL_anacostia_appendixC_nutrients_BOD.pdf (135KB)
Appendix D TMDL_anacostia_appendixD_nutrients_BOD.pdf (82KB)
NPS Tech Memo TMDL_anacostia_NPS_Tech_Memo_nutrients_BOD.pdf (20KB)
PS Tech Memo TMDL_anacostia_PS_Tech_Memo_nutrients_BOD.pdf (38KB)
Comment Response Document CRD_anacostia_nutrients_BOD.pdf (210KB)
Modeling Report TMDL_anacostia_nutrients_BOD_modeling_report.pdf (2276KB)


Contact Information

Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3572.