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West Point Treatment Plant resumes full compliance with environmental permits


King County’s West Point Treatment plant resumed compliance with its state and federal environmental permits earlier this week, with effluent discharges to Puget Sound meeting or surpassing strict standards for pollutant removal. Plans are underway to replace temporary equipment and complete long-term repairs by the end of 2017.


King County’s West Point Treatment Plant is once again operating at full capacity, with the highly treated effluent sent to Puget Sound once again meeting stringent standards required under state and federal environmental permits. 

The plant resumed the ability to treat its wastewater to the secondary level in late April, which requires beneficial bacteria to break down organic solids and remove pollutants from water that is disinfected, dechlorinated and returned to Puget Sound. 

The loss of power and heat after the plant was damaged by flooding on Feb. 9, 2017, put the biological process into hibernation and temporarily limited treatment capabilities. Restoring the health of the biology required a careful combination of time and scientific expertise to avoid damaging this delicate, living system.

With the secondary process now fully functional, water from the treatment process now complies with permits administered by the Washington State Department of Ecology because more than 90 percent of its typical pollutants are removed before discharge to Puget Sound. 

Plant operations employees will continue remaining restoration work, focusing on completing interim repairs and replacing temporary equipment by the end of the year.   

In response to the bypasses and the temporarily limited treatment that occurred in the weeks after the plant was damaged in February, King County has committed to increasing its water quality monitoring in Puget Sound. 

Additional information on West Point’s restoration is online. For ongoing updates on water quality, please visit the West Point Marine Water Quality Monitoring information page.