The Washington Department of Ecology has issued a $21,000 fine to the Midway Sewer District in southwestern King County for allowing raw sewage to flow into McSorley Creek in September 2020.
An estimated 1.2 million gallon spill from a malfunctioning pump station in Kent prompted a temporary closure of Saltwater State Park in Des Moines – where the creek empties into Puget Sound next to a public beach – due to high bacteria levels. A fish kill also was reported in the stream following the spill.
“With the right response, this could have been a minor incident that did not result in a beach closure or fish kill,” said Rachel McCrea, Ecology regional Water Quality Program Supervisor. “Reliable operations and maintenance practices are critical in protecting public heath and the environment.”
Ecology’s investigation found that the pump station at 26211 Pacific Highway South lost power for unknown reasons on the afternoon of Thursday, Sept. 10, 2020. An alarm system notified an on-call staff person by telephone, but the alert was disregarded, based on an assumption that maintenance activities in the area triggered the signal.
Field staff who visited the same pump station the following morning did not notice that a sewage overflow was taking place.
A district superintendent who visited the station at 7 a.m. on Monday, Sept. 14, noticed the overflow, restarted the pump, and began coordinating a cleanup. The district also began sampling the creek and Puget Sound to provide data needed for beach and park closure decisions until it was safe to reopen.
In addition to the park closure, a community member photographed and reported dead cutthroat trout and sculpin in the creek on Sept. 17. The fish are strongly suspected to have died due to low oxygen and high ammonia from the raw sewage that flowed through the stream over five days. The creek’s late-summer low flow would have provided little dilution to the sewage.
Based on follow-up water quality sampling, the park re-opened on Oct. 22.
Since the incident, the sewer district has replaced alarm systems at its pump stations and added sewer line sensors. The roughly $90,000 in upgrades will enable district staff to respond rapidly to prevent or contain overflows. The district also has re-trained its staff on steps to follow when receiving alarm signals and inspecting pump stations.
“The Midway Sewer District understands and takes our responsibility of protecting the public and the environment seriously,” said Marc Montieth, General Manager. “We conducted a thorough investigation into the sewage spill that occurred last September and assisted Ecology with its independent investigation. We accept responsibility for the overflow and have taken measures both in training and capital investment to address the causes as well as minimize any potential for future spills.”
Water quality penalty payments to Ecology are placed into the state’s Coastal Protection Fund, which provides grants to public agencies and tribes for water quality restoration projects. The Midway Sewer District may appeal the penalty to the Washington State Pollution Control Hearings Board.