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Carnation Treatment Plant

Carnation Treatment Plant

The Carnation Treatment Plant has been a local component of King County’s regional wastewater treatment services since beginning operations in 2008. The Carnation Treatment Plant is consistently recognized for award-winning compliance with state and federal effluent permit limits.

May 2023 Update

View the May 2023 newsletter to learn more about the path of water through Carnation, information on upgrades on the treatment plant facility, and what not to flush!

Newsletter Format: English or Spanish
Accessible Format: English or Spanish

aerial view of the Carnation Treatment PlantCarnation Treatment Plant aerial view

Located in the downtown Carnation, the treatment plant helps to support the regional system by treating wastewater in Carnation’s growing area. Carnation serves about 2,000 people every year, with the capacity to serve up to 4,000 by 2030.

At Carnation, we treat wastewater by combining standard biological treatment processes with a state-of-the-art membrane filtration system that traps bacteria and organic material. The Carnation Treatment System collects wastewater from pipes owned and maintained by the City of Carnation . After advanced treatment at the Carnation plant, recycled water is sent to a wetland enhancement site at the Chinook Bend Natural Area. Excess solids are sent to South Treatment Plant in Renton for further treatment.

Learn more:

  • See how Carnation’s Treatment System works here
  • Get the facts on the Carnation Treatment System’s operations here
  • Learn how Carnation contributes to a sustainable future for the surrounding community and environment
  • Explore educational opportunities here

Please report odor concerns and sewer-related incidents right away to support timely investigation.

Where to report:

  • 24-hour emergency and odor reporting: 206-263-1760
  • Carnation Administration: 206-263-1760
Contact us

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

4405 Larson Ave.
Carnation, WA 98041

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