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 through August 5, 2025
  Public Review / Comment Period of 1st Draft
• July 15, 2025
  Public Meeting to Describe Proposed Changes
• Winter 2026
  Public Review / Comment Period of 2nd Draft and 2nd 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 (scheduled to take effect July 2021)
• Spring / Summer 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

Initiation

August 1, 2024: The Department of Ecology reissued the National Pollutant Discharge Elimination System (NPDES) Phase I Municipal permit (Ecology Permit).

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) 
• Public meeting and comment period #1: 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
• Public meeting and comment period #2: Fall/Winter 2025/2026 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.