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Most King County offices will be closed on Thursday and Friday, for the Thanksgiving holiday.  
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Wastewater Treatment Division (WTD) and Novel Coronavirus (COVID-19)

WTD operations staff remain on the job 24/7 to ensure the region’s wastewater treatment service continues. Following the guidance of Seattle-King County Public Health, our offices are closed to the public and all facility tours are suspended until further notice. Please check back periodically for updates.

For questions about COVID-19, we encourage people to visit the Public Health – Seattle & King County website: and subscribe to the Public Health Insider blog:

The Carnation Treatment Plant, located in the City of Carnation, serves about 2,000 people in Carnation’s urban growth area, with capacity to serve up to 4,000 in 2030.

The plant is part of King County's regional system. At design capacity, the plant is expected to treat 480,000 gallons of wastewater a day. The collection system, owned and maintained by the City of Carnation , delivers sewage to the plant from residential and commercial customers.

In addition to the reclaimed water, the plant has been designed with numerous “green” features that minimize impacts on the environment, conserve resources and maximize energy efficiency.

rsz_5553778379_21b748822b_bCarnation Treatment Plant aerial view

View more photos on our Flickr site  .

Contact us

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

4405 Larson Ave.
Carnation, WA 98041

Directions and map