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Elliott West Wet Weather Treatment Station upgrade
King County is planning to upgrade the Elliott West Wet Weather Treatment Station (EWWTS). The upgrade will ensure compliance with stricter environmental regulations, meet the demands of a growing population, and handle a changing climate.
Project description
The Elliott West Wet Weather Treatment Station (EWWTS) is a combined sewer overflow (CSO) facility that was first completed in 2005. Since then, it has stored and treated sewage and stormwater during periods of heavy rain. EWWTS now needs to be upgraded to meet stricter environmental standards and to adapt to changing climate.
This project will ensure that the upgraded facility meets its permit requirements. This is a major investment to ensure King County continues to protect public health and the environment for years to come.
More information about the upgrade plans will be available this summer and fall. To stay updated, subscribe to our email list.
Project update
September 19, 2025
Don’t let your ideas go down the drain!
Provide your input on our Elliott West Wet Weather Treatment Station Upgrade. Starting September 18! Learn about the station, our 30% design, and offer your input.
Go to PublicInput.com/Elliottwestupgrade2025
Previous project updates
- Just over a week left 'til our online briefing on May 29! May 21, 2025
- Have you heard about the upgrade coming to the Elliott West Wet Weather Treatment Station? May 2, 2025
- Maintenance work near Elliott West Facility February 13, February 12, 2025
- Updates on the Elliott West Wet Weather Treatment Station upgrade, June 2024
- Survey for Elliott West Wet Weather Treatment Upgrade project closes Sunday, Sep 24 at midnight! September 22, 2023
- Elliott West Wet Weather Treatment Upgrade project website is now LIVE! September 5, 2023
- New Project Alert! The Elliott West Wet Weather Treatment Station is getting an upgrade and we need your input! August 25, 2023
Project schedule
Our team is in the early stages of designing the needed upgrades to EWWTS. Project timelines may change due to a number of factors. We will provide updates as our work progresses and any schedule changes are needed.