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Water Quality > Stormwater > Municipal Stormwater General Permit
Municipal Stormwater General Permit Information
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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.
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