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King County working with Seattle City Light to ensure power reliability at West Point Treatment Plant


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Public Affairs

King County working with Seattle City Light to ensure power reliability at West Point Treatment Plant


King County and Seattle City Light are investigating options for increasing power reliability at the West Point Treatment Plant to ensure continued environmental protection, following multiple power interruptions in the last few years that have interfered with normal wastewater treatment operations.


The King County Wastewater 21_WP_equipmentTreatment Division (WTD) and Seattle City Light (SCL) are working together to improve the reliability of power supplied to the County’s West Point Treatment Plant so the facility can continue to safely treat wastewater and protect the environment.

Overflows at the treatment plant have been attributed to disruptions in power provided by Seattle City Light. Power disruptions can cause plant equipment to turn off, which in turn triggers the plant to perform as it was designed and protect the plant and employees by directing wastewater and stormwater flows through the emergency bypass into Puget Sound. Power disruptions at the treatment plant are particularly troubling during heavy storms when the facility is operating near or at full capacity.

On Feb. 3, Washington State Department of Ecology (Ecology) issued a fine and Administrative Order that prescribes actions WTD must take to meet Ecology’s requirements. King County agrees with the scope of Ecology’s order, which outlines work that has already started at West Point.

King County partnered with SCL in 2019 to study the power supply issues and has completed or begun all of the work identified in Ecology’s order. In fact, WTD is looking to go further than the order requires and is working with SCL to expand the options for their provision of power. At peak demand, West Point requires 10 Megawatts – a enough energy to power 11,000 homes.

The Wastewater Treatment Division has made significant improvements the past four years to improve operational performance:
o Improved safety protocols
o Modified standard operating procedures
o Enhanced monitoring protocols
o Rigorous staff training
o Installed new electrical and control systems
o Added redundancy at pump stations
o Made the equipment less sensitive to power fluctuations

Ecology also noted in its administrative order that King County employees did not sufficiently plan work on an upgrade project at South Treatment Plant that resulted in a 79-minute discharge of fully treated wastewater that did not go through a final disinfection process on July 18, 2019. In response, King County has modified its standard operating procedures and trained employees on enhanced systems and equipment monitoring.  

King County’s West Point Treatment Plant


Marie Fiore, 206-263-0284 or

About the King County Wastewater Treatment Division
King County’s Wastewater Treatment Division protects public health and enhances the environment by collecting and treating wastewater while recycling valuable resources for the Puget Sound region. The division provides wastewater treatment services to 17 cities, 17 local sewer districts and more than 1.8 million residents across a 420-square-mile area in King, Snohomish and Pierce counties.