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Stormwater Code & Rules Update

An Example of Stormwater Control Methods
Our Stormwater Code protects people, property, and the environment by controlling how rain water runs off of streets, buildings, and parking lots.

What’s Happening Now?

We are hosting a public meeting on June 10, from 4:00 – 6:00 p.m. about the 2016 Stormwater Code and Manual Update. We expect to make the draft documents of the 2016 Stormwater Code available before the meeting.

In May 2014, we published the Draft 2015 City of Seattle Stormwater Manual, Volumes 1 through 5, and the appendices. They are available for your review on the project documents page.

Originally, we anticipated making all the changes at one time in 2015, as we had stated in handouts and at various public meetings throughout 2014. However, the Washington State Department of Ecology (Ecology) was delayed in sending their comments to us on our draft proposal. We received over 150 separate comments from Ecology in February 2015 that we're still addressing. Therefore, we are postponing most of our proposed Stormwater Code changes until January 2016.

In the meantime, in April 2015, the City Council and Mayor approved to revise three sections of the 2009 Stormwater Code (SMC 22.800-22.808) proposed to be effective by May 24, 2015. These changes are not the focus of Ecology's review. The changes are:

  • Changing water quality thresholds for roadway projects
  • Exempting Seattle Public Utilities (SPU) water utility projects from flow control, water quality treatment, and green stormwater requirements
  • Granting the Director of SPU discretion to not require flow control requirements for certain combined sewer basins through a Directors' Rule

We will incorporate all other changes into our proposed 2016 Stormwater Code and Manual update, which will be effective in January 2016. Our new rules will replace the current Stormwater code and Directors' Rules, which are administered jointly by us and SPU.

Project Benefits

Our stormwater code protects people, property, and the environment by controlling how rain water runs off of streets, buildings, and parking lots. Stormwater runoff can cause flooding, landslides, and erosion that can damage our homes, businesses, and property. Stormwater runoff carries oil and grease, fertilizers, pesticides and other toxic chemicals to our creeks, lakes, bays, rivers, and other waterways.

The End Result

Our regulations will be equivalent to Ecology's 2012 Stormwater Manual and will address the following topics:

  • Improve stormwater management for new development in Seattle, including green stormwater infrastructure
  • Improve the Construction Site Stormwater Runoff Controls requirements
  • Clarify Pollution Prevention, Good Housekeeping, and Operation and Maintenance
  • Update the Source Control and Water Quality Treatment Practices

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