Power outages last week caused a few of King County’s wastewater treatment facilities to spill more than 10 million gallons of untreated overflow into the Puget Sound and Lake Washington, according to the King County Department of Natural Resources and Parks.
An early morning windstorm on Jan. 13 brought excessive rainfall and wind gusts over 50 mph in some places, leading to regional flooding and power outages for hundreds of thousands of Western Washington residents.
According to the department, a combination of pump station failures caused by power outages and increased rainwater runoff created flooding overflows at the West Point Treatment Plant, Richmond Beach Pump Station, East Pine Pump Station and Medina Pump Station.
While field operators worked to get the pumps running consistently, operators were able to mitigate the amount of the overflow by controlling the partial closing of the emergency bypass gate, according to the department.
King County estimated that approximately 20% of the more than 10 million gallons of untreated water that overflowed into the Puget Sound and Lake Washington was sewage, and 80% was stormwater.
Initially, King County closed a handful of beaches including Richmond, Medina, Golden Gardens, Carkeek and Madrona beaches out of caution. The county announced on Jan. 16 that consecutive days of water quality testing revealed the beaches to be safe. Discovery Park was reopened on Jan. 18.
King County has notified public health and regulatory agencies, according to the press release, and has posted signs at beaches warning people to avoid contact with the water over the next several days as a precaution to protect public health.