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Project update

November 2017

King County’s North Lake Sammamish Flow Diversion project team is working to identify the best options to divert wastewater to the Brightwater Treatment Plant, providing increased wastewater capacity for our growing region.

Watch for updates as the team’s work progresses.

Project description

Currently, flows from the North Lake Sammamish Basin are routed to the South Treatment Plant through the East Side Interceptor (ESI). This project will divert up to 43 million gallons per day of wastewater from the North Lake Sammamish Basin and send them to the Brightwater Treatment Plant.

Project schedule

3Q 2017 Procure design consultant
1Q 2018 Alternative analysis complete 
3Q 2018 Predesign complete
3Q 2019 Final design complete
1Q 2020 Bidding and award
1Q 2020 – 4Q 2021 Construction


Contact us

Contact Monica Van der Vieren community services lead at:



Project location


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