Under the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) helps control the discharge of pollutants into water bodies by regulating point sources. By definition, point sources are discrete conveyances such as man-made ditches, tunnels, channels, or pipes that directly discharge into surface waters. By regulating these forms of discharge, the NPDES hopes to protect the public health and assure the treatment of wastewater.

The main pollutants regulated by the NPDES include conventional pollutants (sanitary wastewater, which consists of domestic wastewater—what people flush down their kitchen sink, for example) and wastewater from commercial and industrial facilities, fecal coliform, oil and grease, toxic pollutants (organic and metals), and nonconventional pollutants (such as nitrogen and phosphorous). Industrial, municipal, or agricultural facilities discharging directly into surface water require NPDES permits. A household connected to a municipal or septic sewer system does not.

NPDES permits can be obtained at a state environmental protection office, or at an Environmental Protection Agency (EPA) regional office (in states without EPA approval to issue permits). The permits limit what can be discharged into the environment and provide established monitoring and reporting requirements. The EPA monitors NPDES compliance with on-site inspections and data review. Failure to comply with a permit's provisions can result in civil and criminal action against the violator.

By maintaining vigilant control of pollutants discharged into surface water, the NPDES helps to prevent harmful contamination of the public's water supply.

Internet Resources

Environmental Health & Safety Online. "NPDE—National Pollutant Discharge Elimination System." Available from http://www.ehso.com/npdes.htm.

U.S. Environmental Protection Agency. "National Pollutant Discharge Elimination System (NPDES)." Available from http://www.cfpub.gov/npdes.