NPDES Phase II Permit


The National Pollutant Discharge Elimination System (NPDES) Permit (Permit) is a federal permit that regulates stormwater and wastewater discharges to waters of the State. While it is a federal permit, the regulatory authority has been passed to the Washington State Department of Ecology (Ecology). The first Western Washington Phase II Municipal Stormwater Permit was issued by Ecology in January of 2007. The current permit term is five years, beginning Aug. 1, 2019, and ending July 31, 2024.

The Permit requires that all affected municipalities create and implement a Stormwater Management Program (SWMP) which addresses five required program elements: 

  • Stormwater Planning
  • Public Education and Outreach
  • Public Involvement and Participation
  • MS4 Mapping and Documentation
  • Illicit Discharge Detection and Elimination
  • Controlling Runoff from New Development, Redevelopment and Construction Sites
  • Operations and Maintenance
  • Source Control Program for Existing Development 

Select cities, such as the City of Marysville, are required to provide additional actions applicable to Total Maximum Daily Load (TMDL) requirements.