The Surface Water Management division coordinates updates to the Stormwater and Site Development Manual (Title 17A). For information about upcoming updates, subscribe to updates.

• Adopted Stormwater Manual, Effective Dec. 5, 2015
  Please note this file is very large and will take some time to download depending on your internet connection.

*If you are downloading the manual, please subscribe to updates, so we can keep you informed of any changes.

• Adopted Stormwater Manual by Volume - You can find specific volumes of the overall document here.

• Library of Supporting documents and historic manuals

Other resources:

• NPDES permit
• Ecology Adopted Stormwater Manual