Sunday, July 10, 2022

New NPDES Permit Coming in 2024

About one year from this month, the Department of Ecology's (DOE) National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater Permit will expire on July 31st, 2024. This will happen as part of the regular 5-year permit cycle. The DOE and permit holders are already hard at work on what the 2024-2029 Permit will look like. 

The changes to the permit make a significant impact on the local requirements for stormwater regulations in Washington State. Significant updates to be proposed to the permit will include:

  • Address tire wear research findings – Road Runoff
  • Update Stormwater Planning & Structural Stormwater Control programs
    • Consider retrofit implementation program for Phase II
  • Enhance Source Control requirements 
    • Street sweeping program
    • PCBs in building materials

NPDES Permit Timeline


  • Fall 2022/Early 2023 - Preliminary drafts of permit sections may be provided for specific permit sections for informal comment.
  • Late Summer/Fall 2023 - Draft Permits will be issued. DOE will hold a formal public comment period, which will include a workshop and hearing, on the draft permits.
  • July 2024 - DOE will make the decision to reissue the NPDES Permits.

Listening sessions were held by the DOE on June 6 and 13, 2022. The presentation can be viewed here. An excellent video of the upcoming changes to the stormwater manual was played during the listening session. I summarized those changes below. You can watch the video on YouTube here.

Early Input

In preparation for the new permit language, several municipal permittees participated in ad-hoc groups hosted by the Washington Stormwater Center and led by local government staff to develop white papers on a variety of topics. The white papers provided early input to the DOE on the next permit cycle and give insight to the opinions of local jurisdictions on how to improve the permit requirements to continue to protect our local creeks. 

The white papers focused on the following areas:

Additional information on the ad-hoc process can be found at


Stormwater Manual Updates

The Eastern Washington and Western Washington Stormwater Management Manuals were previously published on different timelines, which created issues in the process. This permit cycle, DOE will publish both manuals on the same schedule.