The 1972 amendments to the Federal Water Pollution Act (FWPCA, also referred to as the Clean Water Act or CWA) prohibit the discharge of any pollutant to waters of the United States from a point source unless the discharge is authorized by a National pollutant Discharge Elimination System (NPDES) permit. Efforts to improve water quality under the NPDES program traditionally have focused on reducing pollutants in discharges of industrial process wastewater and from municipal sewage treatment plants. Past efforts to address storm water discharges under the NPDES program have generally been limited to certain industrial categories with effluent limitations for stormwater (EPA website, 2004).
Pollutants in stormwater discharge continue to remain a significant source of environmental impact to the quality of waters on the United States. The 1994 National Water Quality Inventory Report to Congress indicates that stormwater discharges from a variety of sources including separate storm sewers, construction, waste disposal, and resource extraction activities are main causes of water quality impairment. Approximately 46 percent of the identified cases of water quality impairment of estuarine square miles surveyed, for example are attributable to storm water runoff.
Stormwater can pick up debris, chemicals, dirt, and other pollutants and flow into a storm sewer system or directly to a lake, stream, river, wetland, or coastal water. Anything that enters a storm sewer is discharged untreated into the water bodies we use for swimming, fishing, and providing drinking water.