Update: Beaches at Discovery Park and in Kitsap County have reopened.

The state Department of Ecology is investigating after failures at King County’s two largest sewage treatment plants led to beach closures in Puget Sound.

About 3 million gallons of untreated sewage spilled into the Puget Sound Friday morning after a failure at the West Point Treatment Plant, according to a statement from the Department of Ecology. For a half-hour, sewage spilled into the water near North Beach in Discovery Park. The spill occurred after backup pumping systems failed during a Seattle City Light power outage, according to King County.

As a result of the spill, Discovery Park’s North and South beaches closed to water contact Friday evening. The Department of Ecology initially said multiple King County beaches were closed, but Public Health — Seattle & King County said only Discovery Park’s beaches were affected.

Kitsap County closed three beaches to water contact, as modeling showed sewage would likely reach the beaches.

On Thursday, there was a different power failure at the Renton Wastewater Treatment Plant. The failure may have interfered with the disinfection of wastewater that emptied into Puget Sound northwest of Duwamish Head in Seattle, according to the statement. The failure lasted about 50 minutes.

County officials reported both incidents to the state and expressed concern with “power reliability,” according to a statement from King County.


The discharges could potentially violate the state’s water quality permits for the facilities, according to the Department of Ecology. Investigators will determine the cause of the recent failures, and the department may take enforcement actions against the county.

King County faced heavy penalties after the West Point plant flooded in 2017, which was also triggered by a power disruption. The scale of the catastrophe was unprecedented in the region, as an estimated 235 million gallons of untreated wastewater, including 30 million gallons of raw sewage, were sent into Puget Sound. The county estimated the damage at $25 million.

Department of Ecology spokeswoman Colleen Keltz said the 2017 flooding is similar to the recent failures as all were triggered by power disruptions. In response to the recent spills, the plants were back online much faster, she said.

“We don’t know yet in looking at the equipment and upgrades they made since 2017 what’s a new problem and what’s the same problem,” Keltz said.

A Seattle Times investigation found that errors in judgment, poor communication, a lack of training, equipment failures and faulty maintenance led to the 2017 flooding. A Department of Ecology investigation mirrored those findings, and the department fined King County $361,000, which was the largest penalty it had issued a publicly-owned wastewater treatment plant.

The county was ordered to make “significant” investments that were estimated to cost $1.35 million to prevent a similar spill in the future, according to the department.

King County officials said Friday that they’ve replaced equipment, updated control systems and increased training of plant operators as a result of the 2017 flooding. In a statement, the county said “the investment paid off” Friday, as West Point plant employees were able to prevent flooding and restore operations in 27 minutes, despite conditions similar to those in 2017.