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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

King County's Regional wastewater conveyance and treatment system

Our service area and facilities, April 2014King County protects water quality and public health in the central Puget Sound region by providing high quality and effective treatment to wastewater collected from our local sewer agencies. The county's Wastewater Treatment Division (WTD) serves about 1.5 million people within a 415-square-mile service area, which includes most urban areas of King County and parts of south Snohomish County and northeast Pierce County.

King County's wastewater system includes:

Construction on the Brightwater Treatment Plant, the system's third regional treatment plant, began in 2006. Treatment plant operations began in September 2011; conveyance system and outfall began full operations in fall 2012. Final restoration work at construction sites will continue through late 2013 and early 2014.