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Treatment process at Carnation

Learn about the process we use to clean wastewater at Carnation.

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.

Graphic displaying the Carnation Treatment Plant treatment process steps

Download the treatment process diagram (PDF) to learn more.

NPDES permits

The Washington State Department of Ecology administers National Pollutant Discharge Elimination System (NPDES) permits under authority delegated to the department by the U.S. Environmental Protection Agency. These permits outline the conditions under which King County can discharge treated wastewater.

Learn more about Carnation and other King County wastewater permits.