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Monitoring update: February 2018

King County has completed analysis of water quality monitoring data that were collected during the restoration of the West Point treatment facilities damaged by the flooding of the plant that occurred on February 9, 2017. The West Point Flooding Event Water Quality Monitoring Report (27MB) was peer-reviewed by three external scientists and presents the data and findings regarding the effects of the flooding event on effluent and marine water quality.

Restoration update: February 2018

The West Point Treatment Plant resumed normal operation on May 11, 2017, and is again in compliance with its strict permit limits under state and federal clean-water laws.

Infographic - what is happening at West Point Treatment Plant
Visit the marine monitoring page to learn about the water quality monitoring that King Count has conducted while West Point Treatment Plant was being restored and the ongoing monitoring. You can find our monitoring plan, frequently asked questions, and contact information for questions and concerns. We will post monitoring data and summaries every two weeks. Visit the environmental monitoring page for permit-required and supplemental monitoring information.


West Point Treatment Plant suffered severe equipment failure and flooding early in the morning of Feb. 9, 2017, while operating at maximum capacity during a storm. The flooding severely damaged mechanical and electrical systems needed to provide secondary treatment of the wastewater and provide heat to the solids reduction biology, which essentially crippled the plant’s solids handling capabilities. For three months, the plant was unable to treat to secondary levels required under its state and federal permits.

In response to the incident, WTD completed a number of upgrades and improvements at West Point following the recommendations of its initial root cause analysis and an independent review commissioned by the King County Council.  All repairs critical to plant operations were completed in April 2017. The plant resumed full compliance with environmental permits in May, and all long-term repairs and upgrades were completed as-scheduled by the end of 2017. Improvements also include strengthened safety training and clearer emergency protocols to protect workers and equipment.

1511_west-point-treatment-processView larger version .

wp-employee-working-on-pump_600Employee working on pump equipment. View more photos on our Flickr site .