Puget Sound Olympia

Municipal Stormwater

Water Quality > Stormwater > Municipal Stormwater General Permit

Municipal Stormwater General Permit Information

Salmon spawning


Phase I | Phase II Eastern | Phase II Western | WSDOT permits

Bio-swale (vegetated depression by a road)

Permit Components

Help and guidance, organized by the sections of the permits.

Stepped pools

Permittee Resources

Additional resources for permittees, such as training and grants.

Vacuum street sweeper

Stormwater Manuals

Western | Eastern | Technical Assistance

Keeping pollutants out of municipal water systems

New item The 2014 Permit and Stormwater Manual Modification public comment period has CLOSED. Ecology is reviewing comments; see the modification page for the estimated completion date.

Many urban areas that collect stormwater runoff in municipal separate storm sewer systems (MS4s) are required to have a permit under the federal Clean Water Act.

The Environmental Protection Agency (EPA) stormwater regulations established two phases — Phase I (for medium and large MS4s) and Phase II (for smaller MS4s) — for the municipal stormwater permit program. (See our Municipal Stormwater Permittee Lists for a listing of the permittees covered by the Municipal Stormwater Permits.)

In Washington State, the Department of Ecology develops and administers National Pollutant Discharge Elimination System (NPDES - a section of the Clean Water Act) municipal stormwater permits.


New item Stormwater Control Transfer Program: draft guidance available for comment

2016 Grant Applications

2012 Municipal Stormwater Permit Appeals

2014 Permit Modification