Stormwater Codes and Rules Update - Accomplishments

Project Outcomes

The 2021 Stormwater Code and Manual became effective on July 1, 2021. These rules replaced the 2016/2017 Stormwater Code and Directors' Rules, which were administered jointly by SDCI and Seattle Public Utilities (SPU). The 2016 Stormwater Code and Manual had previously replaced the 2009 Stormwater Code and Manual. See Documents page for the 2009 and 2016 Code and Manual versions and associated forms and documents.

Key Milestones

  • April 1 - March 16, 2020
    Public Review/Comment Period #1
  • July 2020
    We submitted our Draft Stormwater Code and related Stormwater Manual to Ecology for review
  • November 1 - November 20, 2020
    Public Review/Comment Period #2
  • Winter 2020
    We completed the State Environmental Policy Act environmental review
  • January 11 - February 19, 2021
    Public Review/Comment Period #3
  • Spring 2021
    The legislative process and formal public review period began for the 2021 Stormwater Code Update
  • Spring 2021
    We began our Directors' Rule process and formal public review for the 2021 Stormwater Manual Update
  • July 2021
    The 2021 Stormwater Code and Manual became effective

Project Purpose

To make sure our regulations are equivalent to Ecology's 2019 Stormwater Manual as required as a condition of our NPDES 2019 Municipal Stormwater Permit (Ecology Permit). Also, changes were made to help reduce stormwater impacts to combined sewers, add options for On-site Stormwater Management, to align thresholds that trigger stormwater requirements, and to clarify existing requirements.

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