Municipal Stormwater Permits
The Phase I Municipal Stormwater Permit regulates discharges from municipal separate storm sewer systems (MS4s) owned or operated by the state's largest cities and counties.
The Phase II Municipal Stormwater Permits regulate discharges from certain "small" MS4s in Washington.
We issue two Phase II permits:
- The permits also apply to public separate storm sewer systems operated by other types of public entities located in a Phase I or II city or county. Examples include ports, prison complexes, park districts, universities, or diking and drainage districts.
- See Secondary Permittee guidance to determine whoe should apply for permit coverage.
Washington State Department of Transportation (WSDOT) Municipal Stormwater Permit
The WSDOT municipal stormwater permit regulates discharges from state highways, rest areas, park-and-ride lots, ferry terminals, and maintenance facilities within the urbanized areas of the state.
Who's covered under the municipal stormwater permits?
View a map of Phase I and Phase II Municipal Stormwater Permit area boundaries
The 1990 Phase I regulation requires medium and large cities or certain counties with populations of 100,000 or more to obtain NPDES permit coverage for their stormwater discharges.
The 1999 Phase II regulation requires small MS4s in U.S. Census Bureau defined urbanized areas, as well as MS4s designated by the permitting authority, to obtain NPDES permit coverage for their stormwater discharges.
Keep in touch with us
Join our municipal stormwater permit email list to receive updates about our permits.
Apply for permit coverage
Apply through SecureAccess Washington and use the WQWebPortal to submit your NOI (Notice of Intent).
For guidance about applying, changing, or implementing and complying with your municipal stormwater permit see the municipal stormwater guidance page. Stormwater manuals provide stormwater permit implementation and management guidance. For more general stormwater permit guidance, see the stormwater guidance page.
Frequently asked questions
Have a question? Check out our frequently asked questions page.
Are our permits successful at preventing or reducing pollution from stormwater runoff? Check out the Stormwater Action Monitoring program and our other results on the stormwater monitoring page.
Phase II Municipal Stormwater Permit Writer
Phase I Municipal Stormwater Permit Writer
Skagit, Snohomish, and Whatcom counties, and the cities of: Anacortes, Arlington, Bellingham, Burlington, Everett, Ferndale, Granite Falls, Lake Stevens, Lynden, Marysville, Mill Creek, Monroe, Mount Vernon, Mukilteo, Oak Harbor, Sedro-Woolley, and Snohomish
The cities of: Bellevue, Bothell, Brier, Clyde Hill, Duvall, Edmonds, Issaquah, Kenmore, Kirkland, Lake Forest Park, Lynnwood, Medina, Mercer Island, Mountlake Terrace, Redmond, Sammamish, Seattle, Shoreline, Snoqualmie, and Woodinville
Kitsap and King County, and the cities of: Algona, Auburn, Bainbridge Island, Black Diamond, Bremerton, Burien, Covington, Des Moines, Federal Way, Kent, Maple Valley, Newcastle, Normandy Park, Pacific, Port Orchard, Poulsbo, Renton, SeaTac, and Tukwila
Pierce county, and the cities of: Bonney Lake, Buckley, Dupont, Edgewood, Enumclaw, Fife, Fircrest, Gig Harbor, Lakewood, Milton, Orting, Port Angeles, Puyallup, Steilacoom, Sumner, Tacoma, and University Place
Clark, Cowlitz, and Thurston Counties, and the cities of: Aberdeen, Battle Ground, Camas, Centralia, Kelso, Lacey, Longview, Olympia, Tumwater, Vancouver, and Washougal
Chelan, Douglas, and Yakima counties, and the cities of: East Wenatchee, Ellensburg, Kennewick, Richland, Selah, Sunnyside, Union Gap, Wenatchee, West Richland, and Yakima
Asotin, Spokane, and Walla Walla counties, and the cities of: Asotin, Clarkston, Moses Lake, Pasco, Pullman, Spokane, Spokane Valley, and Walla Walla
WSDOT Statewide Permit Writer