King County Stormwater Management Program Plan

Our Stormwater Management Program (SWMP) Plan lists our proposed actions to comply with the Phase I Municipal Stormwater National Pollutant Discharge Elimination System (NPDES) Permit (Phase I Permit) issued by the Washington State Department of Ecology.

The SWMP is also attached to our Annual Report, which provides information for our previous year's work related to the Phase I Permit. 

The draft 2025 Stormwater Management Program Plan is currently open for public comment. Please let us know your feedback to help shape the SWMP Plan. Comments submitted after March 31 will be considered for next year's program plan.

Download document here:

2025 DRAFT King County Stormwater Management Program Plan (1.5 MB)