We develop and administer Clean Water Act National Pollutant Discharge Elimination System (NPDES) municipal stormwater permits in Washington. The Western Washington Phase II permit requires local governments to manage and control stormwater runoff so that it does not pollute downstream waters.
The current permit is effective Aug. 1, 2024, and expires on July 31, 2029.
Overview of permit timelines
View
permit timelines
for continuing permittees. These timelines provide an overview of major deadlines for implementing permit requirements.
Annual reports for the calendar year are due by
March 31 the following year.
Municipal stormwater permit guidance
For guidance about applying, changing, or implementing and complying with your municipal stormwater permit see
municipal stormwater guidance
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
Permit history
Keep in touch with us
Join our
municipal stormwater permit email list
to receive updates about this permit.