Section 303(d) of the Clean Water Act and the U.S. Environmental Protection Agencys (EPAs) Water Quality Planning and Management Regulations (codified at Title 40 of the Code of Federal Regulations (CFR) Part 130) require states to develop Total Maximum Daily Loads (TMDLs) for impaired waterbodies. A TMDL establishes the amount of a pollutant that a waterbody can assimilate without exceeding its water quality standard for that pollutant. TMDLs provide the scientific basis for a state to establish water qualitybased controls to reduce pollution from both point and nonpoint sources to restore and maintain the quality of the states water resources (USEPA 1991). A TMDL for a given pollutant and waterbody is composed of the sum of individual wasteload allocations (WLAs) for point sources and load allocations (LAs) for nonpoint sources and natural background conditions. In addition, the TMDL must include an implicit or explicit margin of safety (MOS) to account for any uncertainty in the relationship between pollutant loads and the quality of the receiving waterbody. In the District of Columbia (the District), the Anacostia River and its tributaries have been variously designated as Class A, B, C, D and E waters (District of Columbia Municipal Regulations 21.11.1101.1). According to the Districts 2006 and 2008 Water Quality Assessment (305(b) and 303(d)) Integrated Reports, the Upper Anacostia River (DCANA00E) and Lower Anacostia River (DCANA00E) are impaired by trash (District of Columbia, Department of Health 2006 and District of Columbia, Department of the Environment 2008). The District divides the portion of the Anacostia River watershed within its boundaries into two segments. The Lower Anacostia is the portion of the river extending from the mouth of the river to the John Philip Sousa Bridge and Pennsylvania Avenue. The Upper Anacostia is the portion from the bridge to the Maryland border. The upper and lower segments of the Anacostia were listed on DCs 1998 Section 303(d) List as impaired by biochemical oxygen demand (BOD), bacteria, organics, metals, total suspended solids (TSS), and oil and grease. DC developed these TMDLs between 2002 and 2008 to address all these impairments in its portion of the Anacostia.