As authorized by the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States. Point sources are discrete conveyances such as pipes or man-made ditches.

A common nonpoint source of pollution is runoff carried into water through rainfall or snowmelt. Additions of pollutants into waters covered by the CWA from nonpoint sources do not require NPDES permits. Nonpoint sources are typically left to the individual states to regulate through mandatory or voluntary mandates.

“Discharge of a Pollutant” – any addition of any “pollutant” or combination of pollutants to “waters of the United States” from any “point source,” or any addition of any pollutant or combination of pollutants to the waters of the “contiguous zone” or the ocean from any point source other than a vessel or other ...

The CWA defines “discharge of a pollutant” as “any addition of any pollutant to navigable waters from any point source.” CWA Section 1362(12)(A).