Stormwater Code and Manual Update 2026 - Timeline

Timeline

August 1, 2024
The Washington State Department of Ecology (Ecology) re-issued our National Pollutant Discharge Elimination System (NPDES) Phase I Municipal Stormwater Permit (Ecology NPDES Permit).
August 1, 2024 - July 31, 2029
Our Ecology NPDES Permit is effective
July 1, 2025
Submit Draft Stormwater Code and related Stormwater Manual to Ecology for review
July 8 - August 8, 2025
Public Review / Comment Period of First Draft
July 15, 2025
Public Meeting to Describe Proposed Changes
Fall 2025 / Winter 2026
Second Public Review and Virtual Public Meeting
Winter / Spring 2026
Complete State Environmental Policy Act environmental review
Spring 2026
Legislative process and formal public review for 2026 Stormwater Code Revision
Spring 2026
Directors' Rule process and formal public review for 2026 Stormwater Manual Update
July 1, 2026
Our updated 2026 Stormwater Code and related Stormwater Manual (Directors' Rule) are scheduled to take effect

Phase 1 - Equivalency Items and Ecology review

Address items related to Ecology Permit equivalency (e.g., source control BMPs, wetland hydroperiod, pavement maintenance projects, bioretention soil changes, etc.)
Draft Stormwater Code and Manual submittal to Ecology: July 1, 2025
Ecology review of Draft Stormwater Code and Manual: July - December 2025 (up to 180 days)
First public meeting and comment period: Summer 2025

Phase 2 - Non-Equivalency Items and State Environmental Policy Act (SEPA)

Address items that are not related to Ecology Permit equivalency (e.g., stormwater/combined sewer mainline extensions, combined sewer flow control standard/threshold, etc.)
SEPA process
Second public meeting and comment period: Fall 2025 / Winter 2026 after we receive Ecology comments on the Draft Stormwater Code and Manual

Phase 3 - Legislative and Rule Making Process and Adoption

Spring 2026: Director's Rules (2021 Seattle Stormwater Manual and New SPU Public Drainage System) Public Notice of Rulemaking comment period.
Spring 2026: City Council review of the Stormwater Code Ordinance
May 2026: City Council Transportation & Utilities Committee presentation and vote for approval of the Stormwater Code Ordinance
May 2026: Full City Council consideration of the Stormwater Code Ordinance

Effective Date: Our updated Stormwater Code and related Director's Rules are scheduled to take effect on July 1, 2026.