Section 303(d) of the federal Clean Water Act (CWA) and the U.S. Environmental Protection Agency (EPA)s 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. Upper North Branch Potomac River (basin code 02141005), located in Garrett County, Maryland, was identified on the States list of WQLSs as impaired by metals (1996 listing), sediments (1996 listing), nutrients (1996 listing), low pH (1996 listing), and impacts to biological communities (2002 & 2004 listing). Also in 2002, Spring Gap within this basin was listed as impaired by methylmercury in fish tissue. This document, upon EPA approval, addresses the nutrient impairment in Upper North Branch Potomac River; the mercury, pH, and impacts to biological communities impairments will be addressed at a future date. The metals and sediment listings will be addressed in 2006.