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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.


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. Therefore, due to the delay, 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). 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


Draft documents for the 2016 City of Seattle Stormwater Code and Manual (submitted to Washington State Department of Ecology April 23, 2014):

The following documents outline the April 2014 summary of changes we made to the code and manual:

Codes & Directors' Rules

2015 Stormwater Code Revision to the 2009 City of Seattle Stormwater Code Legislative Package approved by the Mayor and City Council, effective May 24, 2015:

The Director of Seattle Public Utilities proposed rule DWW-430.1, Flow Control Requirements for Projects in Identified Public Combined Sewer Basins. It was effective May 28, 2015.

Previous Public Meetings

Public Meeting: June 3, 2014

Meetings & Events


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