This document, upon approval by the U.S. Environmental Protection Agency (EPA), establishes Total Maximum Daily Loads (TMDLs) of Polychlorinated Biphenyls (PCBs) in the Baltimore Harbor, Curtis Creek/Bay, and Bear Creek portions of the Patapsco River Mesohaline Tidal Chesapeake Bay Segment. Section 303(d) of the federal Clean Water Act (CWA) and the EPAs implementing regulations direct each State to identify and list waters, known as water quality limited segments (WQLSs), in which current required controls of a specified substance are inadequate to achieve water quality standards (WQSs). For each WQLS, the State is to either establish a TMDL of the specified substance that the waterbody can receive without violating WQSs, or demonstrate that WQSs are being met (CFR 2011b). Maryland WQSs specify that all surface waters of the State shall be protected for water contact recreation, fishing, and the protection of aquatic life (COMAR 2011a). Additionally, the specific designated use of the Baltimore Harbor, Curtis Creek/Bay, and Bear Creek portions of the Patapsco River Mesohaline Tidal Chesapeake Bay Segment is Use II Support of Estuarine and Marine Aquatic Life and Shellfish Harvesting (COMAR 2011b). The Maryland Department of the Environment (MDE) has identified the Patapsco River Mesohaline Tidal Chesapeake Bay Segment (Integrated Report Assessment Unit ID: PATMH) on the States 2010 Integrated Report as impaired by nutrients nitrogen and phosphorus (1996), sediments (1996), trash and debris (2008), and impacts to biological communities (2004).