National Pollutant Discharge Elimination System (NPDES)


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The NPDES permit program, created in 1972 by the Clean Water Act (CWA), helps address water pollution by regulating point sources that discharge pollutants to waters of the United States. The permit provides two levels of control: technology-based limits and water quality-based limits (if technology-based limits are not sufficient to provide protection of the water body).
Under the CWA, EPA authorizes the NPDES permit program to state, tribal, and territorial governments, enabling them to perform many of the permitting, administrative, and enforcement aspects of the NPDES program. In states authorized to implement CWA programs, EPA retains oversight responsibilities. Currently 46 states and one territory are authorized to implement the NPDES program.

Types of Permits

An NPDES permit is typically a license for a facility to discharge a specified amount of a pollutant into a receiving water under certain conditions. Permits may also authorize facilities to process, incinerate, landfill, or beneficially use sewage sludge. The two basic types of NPDES permits issued are individual and general permits.

  • An individual permit is a permit specifically tailored to an individual facility. Once a facility submits the appropriate application(s), the permitting authority develops a permit for that particular facility based on the information contained in the permit application (e.g., type of activity, nature of discharge, receiving water quality). The authority issues the permit to the facility for a specific time period (not to exceed five years) with a requirement that the facility reapply prior to the expiration date.
  • A general permit covers a group of dischargers with similar qualities within a given geographical location. General permits may offer a cost-effective option for permitting agencies because of the large number of facilities that can be covered under a single permit.

Additional Resources

Public Participation in the NPDES Permit Issuance Process - Overview of the NPDES permitting process, highlighting opportunities for public involvement.

Primer for Municipal Wastewater Treatment - Overview of municipal processes used to treat domestic wastewater before discharge to the nation's waters.

Clean Water Act Analytical Methods - More information on laboratory analytical methods and test procedures that are used to analyze the chemical, physical, and biological components of wastewater and other environmental samples that are required by the Clean Water Act (CWA).