The National Pollutant Discharge Elimination System (NPDES)
The NPDES program was established by the Clean Water Act Clean of 1972.
Initially, the NPDES program focused on decreasing easily identifiable sources of major pollutants: industrial process wastewater and municipal sewage. The program tracks individual point sources and requires the discharges of pollutants to be minimized through effluent limits set by water quality standards.
Through time, as the NPDES program was implemented, it became more obvious that other sources of water pollution were also significant causes of water quality impairment.
Stormwater runoff is a leading cause of impairment to the nearly 40 percent of surveyed U.S. water bodies which do not meet water quality standards. Impairment means these waters are not safe to swim in, they cannot be used for drinking (if so designated), and/or the fish living in the waters are not safe to eat.
The Clean Water Act was amended by Congress in 1987 to require the Environmental Protection Agency (EPA) to implement a two-phased program to regulate stormwater discharges under the NPDES permit program.