A Total Maximum Daily Load (TMDL) is a regulatory term in the U.S. Clean Water Act, describing a value of the maximum amount of a pollutant that a body of water can receive while still meeting water quality standards. Alternatively, TMDL is an allocation of that water pollutant deemed acceptable to the subject receiving waters. TMDLs have been used extensively by the United States Environmental Protection Agency (EPA) and state environmental agencies in implementing the Clean Water Act by establishing maximum pollution limits for industrial wastewater dischargers. Fish Brook is a small stream located in the town of Fairfield, Somerset County, Maine, and is a tributary of Messalonskee Stream, which drains in to the Kennebec River. The entire stream drains approximately 11 square miles and flows through a series of agricultural fields and dairy farms before reaching Messalonskee Stream. Landuse in the watershed is a rural mix of forested areas and agriculture with sparse residential development along the major roadways. The channel form of the stream varies between low gradient deadwater areas to moderate gradient areas with cobble substrate that are capable of supporting native brook trout (Salvelinus fontinalis).