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National Pollutant Discharge Elimination System Permits

   grassy pond


WSDOT's 2014 Municipal Stormwater permit, issued by the Washington State Department of Ecology, authorizes and regulates discharges from our stormwater conveyance systems within areas covered by Phase I and Phase II Municipal Stormwater Permits. WSDOT has had a Municipal Stormwater Permit since 1995. 

As a part of the 2014 permit reissuance, WSDOT updated its Highway Runoff Manual and Stormwater Management Program Plan. Both of these are included as appendices in the permit.


The Construction Stormwater General Permit regulates stormwater discharges from construction sites. Projects with particularly sensitive environmental concerns may be required to obtain an individual NPDES construction stormwater permit.


The Industrial Stormwater General Permit regulates stormwater discharges from Washington State Ferries' Eagle Harbor Maintenance Facility. 

Sand and Gravel

The Sand and Gravel General Permit regulates the discharge of pollutants from WSDOT's sand and gravel mining operation.