Municipal Stormwater Permits

Most stormwater runoff, collected in municipal separate storm sewers and discharged to surface waters, is now required to have a permit under the federal Clean Water Act. The Environmental Protection Agency (EPA) stormwater regulations establish two phases (Phase I and Phase II) for the municipal stormwater permit program.

Ecology's Environment Education Guide: Protecting Washington's Waters from Stormwater Pollution

The Phase I and Phase II Municipal Stormwater Permits for Washington State are now available.

Phase I Municipal Stormwater Permit

The Phase I permit regulates discharges from municipal separate storm sewers owned or operated by Clark, King, Pierce and Snohomish Counties, and the cities of Seattle and Tacoma.

Phase II Municipal Stormwater Permits

The Phase II permits cover certain "small" municipal separate stormwater sewer systems (MS4s).

Introduction to Phase II Municipal Stormwater Permits

Western Washington Phase II Municipal Stormwater Permit
The Phase II permit for western Washington applies to all regulated small municipal separate storm sewer systems. It covers at least 80 cities and 5 counties.

Eastern Washington Phase II Municipal Stormwater Permit
The Phase II permit for eastern Washington applies to all regulated small municipal separate storm sewer systems. It covers 20 cities and 8 counties.

Secondary Permittees

Secondary permittees are public entities such as ports; prison complexes; park districts; universities; or diking and drainage districts located in a Phase I or II city or county. They may be required to obtain a permit.

Petition Criteria (PDF)

These are the criteria the Department of Ecology will use to evaluate petitions to include additional jurisdictions under the permit. The petitions are allowed under Federal regulations. The Petition Criteria will be supplemented shortly with a petition form. This form, however, is not needed at this time to submit additional areas for coverage under the permits.