Spills photo identifier

Spills Program

West Point treatment plant sewage spill

(Updated: March 18 - Information on this site is considered to be accurate at the time of posting, but is subject to change as new information becomes available.)

Incident summary

King County’s West Point wastewater treatment plant experienced equipment failure in the early morning hours of Feb. 9 resulting in the discharge of a large amount of untreated combined sewage (mixture of sewage and stormwater runoff) into Puget Sound. The plant is currently providing limited treatment to the wastewater but remains in violation of the discharge permit until the plant is back at full operation.

This is a serious situation. Even though the plant is providing primary treatment and disinfecting the wastewater before it discharges, we are concerned about pollutants getting into the Sound that are normally removed with a fully-functioning secondary treatment system. Those pollutants include metals and chemicals commonly found in wastewater from homes, commercial businesses, and industrial operations. Our number one priority is getting this plant back online and fully functioning.

Active investigation

We care tremendously about the health of Puget Sound and take this situation seriously. We have an active and ongoing investigation into the cause and environmental damage. We are receiving regular updates from King County on its progress to restore the facility.

For water quality investigations, Ecology uses a process of information gathering, investigation, and evaluation of the extent of non-compliance before determining the appropriate enforcement actions. We consider, among other factors, the impacts to water quality and public health, the seriousness of the violations, the history of compliance, the responsiveness to the violation, the steps taken to prevent reoccurrence, and the facts to cause of the incident. Our objective is to develop one comprehensive enforcement response to the incident taking all of these factors into account.

In regard to enforcement action on the West Point incident, Ecology will make its enforcement decision at the end of our investigation when we have reviewed all of the information available, including King County Council’s independent investigation. It is anticipated that an enforcement decision will be made in Summer 2017.

Links to supplemental information

March 23, 2017

On March 23, King County released a restoration update to return the King County West Point Treatment Plant to full wastewater treatment capabilities by April 30.

We are continuing to monitor the situation and are receiving regular updates from the county on its progress to restore the facility.

March 18, 2017

King County held a public briefing on the current status of the wastewater treatment plant sewage spill. The county gave an update and answered questions about the incident and restoration efforts.

Senior staff from Ecology’s Northwest Region Water Quality Section attended to support the county’s effort to manage the spill and get the wastewater treatment plant back online. Ecology is providing technical assistance to the county and working with them to recover the plant so it complies with their water discharge permit and protects Puget Sound water quality.

March 17, 2017

On March 17, King County released a restoration update to return the King County West Point Treatment Plant to full wastewater treatment capabilities by April 30.

March 13, 2017

King County Department of Natural Resources and Parks Director Christie True released a statement on county counsel's motion for expert review of the incident.

March 8, 2017

Ecology’s regional staff received copies of the detailed schedule for restoring treatment systems at the plant and the initial forensic report into the incident.

March 7, 2017

King County held a press conference and stated that it was on schedule to get the plant back online by April 30.

We are continuing to monitor the situation and are receiving regular updates from the county on its progress to restore the facility. We are in the early stages of a full investigation of this ongoing event. Our investigation will take time.

February 21, 2017

Senior staff from the Ecology’s Northwest Region Water Quality Section visited West Point Treatment Plant to observe the damage and restoration efforts, as well as interview plant staff.

After the site visit Ecology requested additional information from King County, including a copy of the initial forensic report into the incident and a detailed schedule for restoring plant operations. County staff gathered and sent most of the requested information over the following weeks.

Second bypass event - February 15, 2017

Ecology received a report from King County in the early morning that they partially reopened the emergency bypass system due to concerns that high flow related to another storm may cause more flooding at the plant.

The plant bypassed a portion of the untreated combined sewage it received that day through the emergency bypass system for a seven-hour period the morning of Feb. 15, and again for a 14-hour period from the late afternoon Feb. 15 through early morning Feb. 16. Ecology’s permit manager stayed in close contact with plant staff to gather information on the latest bypass as well as on the original incident.

Incident summary - February 9, 2017

King County’s West Point Treatment Plant sustained major flooding before dawn, when a pump station failed for reasons that are still under investigation. The flooding severely damaged the facility’s sewage treatment infrastructure and allowed untreated combined sewage and stormwater to enter Puget Sound through an emergency bypass system. King County restored flows back through the treatment plant late on Feb. 9, but at a significantly decreased treatment quality. The plant will continue to discharge partially treated wastewater into Puget Sound while the county works to replace damaged equipment.

Ecology’s permit manager for the West Point facility, located in the Northwest Regional Office, was in contact with county staff throughout the day gathering information about the bypassing and damage done to the plant by flooding. The main priority was to ensure that the county coordinated with state and local health agencies so they could make necessary closures to shellfish harvest areas and to advise the county on beach closures. An additional priority was to understand what steps the plant staff was taking to assess damage and restore flow back through the plant. Ecology’s permit manager kept frequent contact with county staff on Feb. 10 and during the following week as King County continued their initial response to the incident.


Date of Incident & Location:
February 9, 2017

1400 Discovery Park Blvd
Seattle, WA 98199

Responsible Party:
King County

Untreated and partially-treated sewage

Under investigation


King County

Jessie Payne