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Puget Sound Olympia

Municipal Stormwater

Water Quality > Stormwater > Municipal Stormwater General Permit

Municipal Stormwater General Permit Information

Salmon spawning


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Stepped pools

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Vacuum street sweeper

Stormwater Manuals

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Keeping pollutants out of municipal water systems

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 7/8/2016 2019 Western Washington Permit Reissuance

2016 Phase I Permit Modification

Audit Program

Western Washington Phase II Equivalent Manuals

Stormwater Control Transfer Program: draft guidance available for comment