NPDES meaning
NPDES stands for the National Pollutant Discharge Elimination System. It's the permit program created by section 402 of the Clean Water Act in 1972. Under the Act, discharging pollutants from a point source (such as a pipe, ditch or channel) into waters of the United States is unlawful without an NPDES permit.
Who needs an NPDES permit?
- Wastewater dischargers: municipal sewage treatment plants and industrial facilities discharging process wastewater.
- Stormwater dischargers: construction sites disturbing one acre or more (or part of a larger common plan), municipal separate storm sewer systems (MS4s), and facilities in listed industrial categories.
- Others: concentrated animal feeding operations, some pesticide applications and other specific activities.
Who issues NPDES permits?
EPA can authorize states, tribes and territories to run the program. Most states are authorized and issue their own permits, which must be at least as stringent as federal requirements. EPA remains the permitting authority in a few states, including Massachusetts, New Hampshire and New Mexico, the District of Columbia, most territories and most Indian country lands. See our state permit table.
Individual vs. general permits
| Individual permit | General permit | |
|---|---|---|
| Written for | One specific facility | A category of similar dischargers |
| How you get it | Apply; the agency drafts a permit with public notice | Submit a Notice of Intent (NOI) to be covered |
| Typical users | Treatment plants, large industrial dischargers | Construction sites, small MS4s, many industrial facilities |
| Example | A city's wastewater plant permit | EPA's Construction General Permit (CGP) |
Most construction projects are covered by a Construction General Permit after submitting an NOI and preparing a SWPPP.
What an NPDES permit contains
- Effluent limitations: technology-based limits (what controls can achieve) and water-quality-based limits (what the receiving water needs). For construction stormwater, these take the form of required practices, such as erosion and sediment controls and stabilization deadlines.
- Monitoring and reporting requirements, from discharge sampling to inspection reports.
- Special conditions, such as requirements for impaired waters.
- Standard conditions that apply to all permittees, such as duty to comply, recordkeeping and signature requirements.
How to find an NPDES permit or NOI
EPA's eReporting and permit search tools let the public look up NOIs and permit coverage for sites where EPA is the permitting authority, and construction sites under the EPA CGP must post a notice with their NPDES ID. States run their own databases.
Learn the full background in the free NPDES and Clean Water Act lesson.
Sources and official references
Last reviewed: October 25, 2026 · Free general education based on the Clean Water Act, EPA NPDES rules and the EPA Construction General Permit. Your governing permit (EPA, state, tribal or local) controls. This is not legal advice, not EPA-approved, and not a California QSP/QSD or other state credential, and it does not issue a certificate. Nothing you enter on this page is saved or sent.