Stormwater Code and Manual Update 2026 - What & Why

salmon

What's Happening Now? 

Our proposed 2026 Stormwater Code and Manual update is scheduled to be effective on July 1, 2026. Our new rules will replace the current Stormwater code and Directors' Rules, which are administered jointly by us and Seattle Public Utilities. For more information, visit our Background page. 

As part of this process, there will be a public notice and review period for the Draft Directors’ Rule (Stormwater Manual) and City Council Stormwater Code legislation meetings where public comment will be accepted. 

Draft Director’s Rule (Stormwater Manual) Public Review:

  • March 16, 2026 - April 1, 2026

Stormwater Code City Council Public Meetings  (dates to be determined):

  • Governance and Utilities Committee – April 2026
  • Governance and Utilities Committee- May 2026
  • Full Council Adoption – May 2026

Visit our Get Involved page for more information on how to comment and to see past public reviews and meeting

Project Benefits

Our stormwater code protects people, property, and the environment by controlling how rainwater runs off streets, buildings, and parking lots. Stormwater runoff can cause flooding, landslides, and erosion that can damage our homes, businesses, and property. Stormwater runoff carries oil and grease, fertilizers, pesticides and other toxic chemicals to our creeks, lakes, bays, rivers, and other waterways.

The End Result

Our regulations will be equivalent to 2024 Stormwater Management Manual for Western Washington (SMMWW), as required by our Ecology NPDES Phase 1 Stormwater Municipal Permit (NPDES Permit), and will address the following topics: 

  • Required Equivalency Items as identified by Ecology (Appendix 10 of the NPDES Permit)
  • General clarifications to improve usability
  • Improve stormwater management for new development in Seattle
  • Improve the Construction Site Stormwater Runoff Controls requirements
  • Clarify Pollution Prevention, Good Housekeeping, and Operation and Maintenance
  • Updates to Flow Control, Water Quality Treatment, and Source Control Practices 

Construction and Inspections

Sam Steele, Interim Director
Address: 700 5th Ave, Suite 2000, Seattle, WA, 98104
Mailing Address: P.O. Box 34019, Seattle, WA, 98124-4019
Phone: (206) 684-8600
Phone Alt: Violation Complaint Line: (206) 615-0808
Contact Us

Sign Up for Latest Updates

Subscribe

SDCI issues land use, construction, and trade permits, conducts construction and housing-related inspections, ensures compliance with our codes, and regulates rental rules. SDCI is committed to an antiracist workplace and to addressing racism through our work in the community.