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King County’s South Treatment Plant earns coveted “Outstanding Performance Award”


King County’s South Treatment Plant earned the prestigious “Outstanding Performance Award” from the state Department of Ecology for perfect compliance with permit conditions in 2014.


The Washington State Department of Ecology honored King County’s South Treatment Plant with an “Outstanding Performance Award” for perfect compliance with all permit conditions in 2014.

The South Treatment Plant is among 127 wastewater treatment plants statewide that received the recognition. To earn the award, the plant had to pass all environmental tests, collect and analyze all required samples, turn in reports, and operate with no violations of any kind.

The plant also had to meet the overall demands of its National Pollutant Discharge Elimination System (NPDES) permit under the federal Clean Water Act and the state’s Water Pollution Control Law.

In service since 1965, King County’s South Treatment Plant in Renton protects public health and water quality for about 700,000 people in communities south and east of Lake Washington. The plant treats an average of 90 million gallons of wastewater each day, with a capacity to treat up to 300 million gallons during severe storms.

The plant site also hosts the award-winning Waterworks Gardens Park, where art, technology and nature join in a unique way. The park’s extensive network of wetlands acts as a natural treatment system to clean stormwater runoff from the plant site. Waterworks Gardens is open to the public year-round from dawn to dusk.

Additional information about the South Treatment Plant is available online.