Natural Resources Defense Council, Inc. v. Muszynski

The Clean Water Act (CWA) required states to (1) identify waterbodies that could not meet water-quality standards for specified pollutants even after implementation of effluent limitations and (2) establish a total maximum daily load (TMDL) for those pollutants. The TMDL encompassed discharges from both point sources and nonpoint sources and effectively posted a limit on the total amount of a pollutant a waterbody could receive over a period of time. The TMDL was required to implement the applicable water-quality standard considering seasonal variations and a margin of safety incorporating any lack of knowledge concerning the relationship between effluent limitations and water quality. The State of New York identified in-state reservoirs that could not meet the drinking-water standard for phosphorus and promulgated TMDLs for the reservoirs in terms of annual loads. New York’s initial water-quality standard for drinking water was 20 micrograms of phosphorus per liter of water (µg/l) based on guidance to maintain water quality for aesthetic purposes. The Environmental Protection Agency (EPA) (defendant) approved the phosphorus TMDLs. The Natural Resources Defense Council (plaintiff) sued the EPA arguing that the TMDLs could not be expressed in annual terms, failed to implement the applicable water-quality standard, and failed to incorporate a margin of safety. The district court ruled in the EPA’s favor, and the Natural Resources Defense Council appealed.