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Combined Sewer Overflow Control

By reducing combined sewer overflows into local water bodies, King County is protecting public health and the environment.
For questions about the King County CSO Control Program, please contact Karen Huber.

Wastewater Treatment Division
King Street Center
201 S. Jackson St., Suite 505
Seattle, WA 98104-3855

Get Directions to our office location in Seattle, Washington.

Real Time CSO Notification

King County is going RainWise


What is RainWise?

More than 450 Seattle homeowners have installed rain gardens and cisterns that are helping to control stormwater runoff and preventing combined sewer overflows as part of the RainWise program in Seattle.

Fall, winter and early spring are great times to start a RainWise project:

  • Plants have time to grow healthy roots and with plenty of rain you don’t need to water them until summer
  • Contractors who install rain gardens and cisterns tend to be more available fall, winter and early spring

Happy rebate customer with her new rain garden! (July, 2014)
Check your eligibility at the RainWise Tools Website at (external link)
or call the Garden Hotline at 206-633-0224.

Learn how these Seattle neighborhoods are becoming RainWise:
Barton and Fauntleroy area
East Ballard/west Phinney area 
Highland Park area  
South Park area 
Sunset Hill area (external link)

King County RainWise is popping up all over! Get started this fall!

Upcoming events
Learn about RainWise at these upcoming events.

Past events
View past RainWise events


Eligible RainWise Basins
Check your eligibility at the RainWise Tools Website at (external link) or call the Garden Hotline at 206-633-0224.

Find contractors. Choose an eligible RainWise contractor (external link).

Be RainWise flier
Download the  Be RainWise flier to learn more about this program.
SpanishSe dispone de más información en español.

Vietnamese_90Hiện có nhiều tin tức bằng tiếng Việt.

News releases

Rain garden resources

Download the rain garden communications and outreach guide (external link).

Check out RainWise projects—take a tour

Check out these 15 RainWise participants who have volunteered to share their experiences on the new RainWise – Ballard Virtual Tour (external link), an online introduction to the wonderful world of rain gardens and cisterns.

Check out RainWise projects -- take a tour
Ballard neighbors show off their rain gardens in new virtual tour.