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The Vashon Treatment Plant, located on Vashon Island, is part of King County's regional wastewater treatment system.

It treats wastewater from homes and businesses within the Vashon Sewer District. Approximately 180,000 gallons a day of wastewater is treated at this facility. A maximum of 1.4 million gallons per day can be treated during the rain/storm season.

Construction updates

August Update: King County contractors will be mobilizing as early as September 5th, 2017 to prepare for construction at the Vashon Bunker Trail pump stations along 103rd Avenue SW and 105th Avenue SW.

1706_construction-map_450See flier  and for more information.

For more information contact: Bibiana Ocheke-Ameh at 206-477-5604 or

Beulah Park and Cove Drip Field

Vashon Treatment PlantVashon Treatment Plant site—after construction

View more photos on our Flickr site  .

Contact us

24 hour emergency and odor reporting:   206-263-1760
Administration:  206-463-7318 

9615 S.W. 171st St.
Vashon, WA 98070

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