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King County wastewater treatment plants earn national environmental awards


Commitment to environmental excellence and an outstanding record of permit compliance earned King County’s wastewater treatment plants several awards from the National Association of Clean Water Agencies.


King County's Wastewater Treatment Division earned several Peak Performance Awards from the National Association of Clean Water Agencies for outstanding compliance with state and federal permit requirements.

The South Treatment Plant in Renton and the West Point Treatment Plant in Seattle each received the Platinum Peak Performance Award. The award honors multiple consecutive years of compliance with effluent limits established by National Pollutant Discharge Elimination System (NPDES) permit under the federal Clean Water Act and the state’s Water Pollution Control Law.

To date, South Treatment Plant is recognized for 17 years of 100 percent permit compliance with its effluent limits, and West Point Treatment Plant has attained 13 years of compliance.

King County’s Vashon and Carnation treatment plants both received Gold awards from NACWA for 100 percent compliance for effluent limits within the past calendar year.

The Brightwater Treatment Plant, which came online in 2011, earned a silver award in 2014.

To comply with state and federal discharge permit effluent requirements, King County’s treatment plants must remove various pollutants from the wastewater in order to meet set limits for biochemical oxygen demand, total suspended solids, fecal coliform counts and total residual chlorine. The permit conditions also require each plant to conduct regular sampling and testing of both its untreated and treated wastewater.

Each day, King County treats and disinfects nearly 200 million gallons of wastewater for more than 1.6 million people in the greater Puget Sound region.

More information about the Peak Performance Awards and list of King County’s prior rankings is available online.