Municipal Stormwater Permit Requirement: Structural Stormwater Controls

The Phase I Municipal Stormwater Permit includes a program requirement for Structural Stormwater Controls (SSC), which requires Permittees to prevent or reduce impacts to waters of the state caused by discharges from the MS4s. The SSC program is intended to address impacts not adequately controlled by other required actions of the permit. 

The permit describes 11 eligible project types that can be implemented to meet the SSC program requirement. Information on the SSC requirement and project types is in Appendix 12 of the Phase I permit.

For the first time, the 2019-2024 Phase I permit requires permittees to meet a minimum level of effort in implementing their SSC programs. 

 SSC Science Synthesis

We took a stepwise approach to the stakeholder process to inform the SSC program requirement for the 2024-2029 permit. We began by conducting a review of available scientific information about the relative environmental benefits of SSC project types. This resulted in the SSC Science Synthesis Report, which will inform the next phase of the stakeholder process: convening a Policy Advisory Committee to develop recommendations for the 2024 Permits.

 SSC Policy Advisory Committee

The SSC Policy Advisory Committee (SSC PAC) met from May-December 2022 and used the SSC Science Synthesis to review the structure and method for measuring the level of effort by permittees implementing SSC programs. The SSC PAC developed recommendations and shared perspectives regarding a proposed approach for a retrofit requirement for the WWA Phase II permit.

Contact Abbey Stockwell at abbey.stockwell@ecy.wa.gov with any questions.

Past SSC PAC Meetings

December 7, 2022 1-4pm Meeting #8

November 15, 2022 1-4pm Meeting #7

October 25, 2022 1-4pm Meeting #6

September 21, 2022 1-4pm Meeting #5

August 24, 2022 1-4pm Meeting #4

July 6, 2022 SSC PAC Meeting #3

May 31, 2022 SSC PAC Meeting #2

May 5, 2022 SSC PAC Meeting #1

Structural Stormwater Control Informational Seminar
Feb. 8, 2022 1 to 4 p.m.
On Feb. 8, we hosted an informational seminar on the current Structural Stormwater Control Program (SSC) in the Phase I Municipal Stormwater Permit as well as similar capital programs implemented by Western Washington Phase II Permittees. This seminar will inform the future discussions of the Policy Advisory Committee on the SSC Program.