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King County’s Vashon Treatment Plant earns environmental compliance award


King County’s Vashon Treatment Plant earned the “Platinum Peak Performance Award” from the National Association of Clean Water Agencies for six years of perfect compliance with its effluent discharge limits


The National Association of Clean Water Agencies recently honored King County’s Vashon Treatment Plant for its sixth consecutive year of perfect compliance with effluent discharge limits under the federal Clean Water Act and the state’s Water Pollution Control Law.

To be eligible for the award, the plant had to meet stringent pollutant removal requirements for its discharges under its National Pollutant Discharge Elimination System (NPDES) permit. 

The Vashon Treatment Plant began operating in 2007 to serve about 1,100 people who live and work within the Vashon Sewer District. The plant treats about 180,000 gallons of wastewater a day, with a capacity to handle up to 1.4 million gallons during storms. 

In 2014, the Vashon Plant earned the State Department of Ecology’s coveted “Outstanding Performance Award” for perfect compliance with all permit conditions.

Additional information about the Vashon Treatment Plant is available online