Stormwater Code and Stormwater Manual Update

In May 2014, DPD published the Draft 2015 City of Seattle Stormwater Code and Stormwater Manual, Volumes 1 through 5, and the appendices. They are available for review on our Stormwater Codes & Rules Update website.

Originally, we anticipated making all the code 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 are still addressing. Therefore, we are postponing most of our proposed Stormwater Code changes until January 2016.

In the meantime, we are proposing legislation to revise three sections of the 2009 Stormwater Code (SMC 22.800-22.808) proposed to be effective by May 25, 2015. These changes are not the focus of Ecology’s review and are also available on our website’s project documents page. 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 Director’s Rule.

SEPA and legislative package documents related to this legislation will be posted on our website in early March.

We will incorporate all other changes into our proposed 2016 Stormwater Code and Manual update, which will be effective in January 2016. Those changes are based on the feedback we received during our informal comment period that ended August 15, 2014 and comments we received from Ecology. Our new rules will replace the current Stormwater code and Directors’ Rules, which are administered jointly by DPD and Seattle Pubic Utilities. Visit our website for more information and to see an updated timeline.

You can submit comments about the proposed changes, and join the Stormwater Code listserv, by sending an email to Please reference the volume number, section number, and page number when providing comments.