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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

January Update: Vashon pump stations Construction update 

Construction at the Vashon Bunker Trail (BT) Pump Stations continues. King County crews are working diligently to complete the work on time. Substantial completion is expected in May, 2018.

Work began in September of 2017 to replace aging equipment and structures at the pump stations. Since then, contractors have made significant progress and construction is expected to be completed on schedule.

One lane closed along 103rd Avenue SW
See flier for more information.

Other construction activities

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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