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King County crews quickly stop an overflow that occurred overnight in South Park during heavy rainfall


King County Wastewater Treatment Division crews responded just after 2 a.m. today to an electrical malfunction at a pump station in Seattle’s South Park neighborhood, quickly stopping the overflow and initiating a cleanup.


King County crews this morning stopped an overflow that occurred overnight in Seattle’s South Park neighborhood, caused by an electrical malfunction at a pump station. Employees initiated a cleanup by mid-morning.

The electrical malfunction — exacerbated by the heavy rainfall — caused a mixture of stormwater and wastewater to back up from maintenance holes and into two local businesses and overflow into the Duwamish River. Staff from Seattle Public Utilities discovered the overflow and alerted King County.

Crews from King County Wastewater Treatment Division responded just after 2 a.m. to the West Marginal Pump Station on West Marginal Way. Crews determined that electrical equipment had malfunctioned and prevented the system from operating normally, causing sewer backups and the release of combined stormwater and wastewater into the river.

The combined flow was released from an outfall located near t̓ałt̓ałucid Park and Shoreline Habitat — formerly 8th Avenue South End Park — along the south bank of the Duwamish River. County employees are working to determine the amount of combined sewer that flowed in the river. King County is working to repair the pump station equipment and clean up any affected property in the area.

The Wastewater Treatment Division reported the overflow to the Washington State Department of Ecology and is coordinating with Public Health – Seattle & King County to determine the impacts to public health based on water quality testing results along the river. It is generally recommended that people avoid contact with local water bodies near a combined sewer overflow outfall for 48 hours following a discharge.

Combined sewers, in which stormwater and wastewater use the same pipes, are part of the original design of the Seattle sewer system. The Wastewater Treatment Division is making largescale investments along the Duwamish River and elsewhere to control the frequency of overflows during storms.

King County Wastewater Treatment Division protects public health and the environment by collecting and cleaning wastewater while recovering valuable resources for a healthy and resilient Puget Sound region. We provide services to 18 cities, 15 local sewer districts, the Muckleshoot Indian Tribe, and nearly 2 million people across a 420-square-mile area in King, Snohomish, and Pierce counties.

UPDATE: This news release was updated on March 15 to make it clear that this was not a "combined sewer overflow" but was instead an overflow that occurred in the combined sewer system. 



Akiko Oda, Wastewater Treatment Division, 206-263-4190