Section 303(d) of the federal Clean Water Act (CWA) and the U.S. Environmental Protection Agencys (EPA) 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. This list of impaired waters is commonly referred to as the 303(d) List. For each WQLS, the State is to either establish a Total Maximum Daily Load (TMDL) of the specified substance that the waterbody can receive without violating water quality standards, or demonstrate that water quality standards are being met. Middle Patuxent River (basin code 02131106, non-tidal watershed) was identified on the States list of WQLSs as impaired by nutrients (1996), sediments (1996), metals-zinc (1996) and impacts to biological communities (2002). This document upon EPA approval, addresses the nutrient impairment in Middle Patuxent River; the listings for sediment, metals-zinc, and impact to biological communities will be addressed at a future date. The metals listing will be addressed in 2006.