The Clean Water Act (CWA) is the foundation for water quality protection in the United States, regulating discharges of pollutants into waterways and establishing water quality standards for industry to follow. Although the basis of the CWA was enacted in 1948, the act was significantly expanded in 1972 and 1977.
The CWA established a nationwide permitting program called the National Pollutant Discharge Elimination System, which regulates water pollution by setting limits on industries that discharge waste into U.S. waterways through point sources (discrete conveyances such as pipes or man-made ditches). In addition, it gave the Environmental Protection Agency authority to enforce the industrial discharge limits and create water quality standards for waterways.
Like the Clean Air Act, the Clean Water Act also authorizes citizens to enforce the law when companies violate their NPDES permits or other water quality standards and federal or state agencies have not taken action.