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Wastewater Treatment

King County, Washington

For questions about the Wastewater Treatment Division website, please send an e-mail message or contact us at:

King Street Center
201 S. Jackson St., Suite 500
Seattle, WA 98104-3855
Phone: 206-477-5371
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Get Directions to our office location in Seattle, Washington.

Staff Contacts

North King County/South Snohomish County projects

Brightwater Treatment System 

In response to increased growth in our region, King County has built a new regional wastewater treatment system called Brightwater. Treatment plant operations began in September 2011. The conveyance system and outfall began full operations in fall 2012. Final restoration work at some of the construction sites is scheduled to continue into 2015.

North Creek Interceptor 

The North Creek Interceptor Project includes completing construction of approximately 10,000 feet of new sewer line, along with connecting this new line to previously constructed pipe. This project is needed to expand the capacity of part of the County's North Creek Interceptor sewer line, to accommodate the projected growth and flows from southwestern Snohomish County. Construction began in 2015 and should take 2 years to complete.