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Project update

June 14,2019

Join us at the Mercer Island Farmers Market on June 23! The market will be located at the north end of Mercerdale Park on Mercer Island. Look for us under the “Go with the Flow” banner logo on our booth. Project staff will share project updates, answer questions and get you signed up for our mailing list. Hope to see you there!

1905_go-with-flow-staffingProject staff sharing information with a community member at Mercer Island Summer Celebration.

State Environmental Policy Act (SEPA) comment period has closed.

Before upgrading the pipes, King County must perform an environmental review as required by the State Environmental Policy Act (SEPA). The SEPA review process involves evaluating how the project will affect the environment.

King County issued a SEPA Determination of Non-significance (DNS) for this project on May 23, 2019. This determination means the County’s SEPA review found that the project will not have significant adverse impacts to the environment. The determination will be reviewed by the Washington State Department of Ecology. View the project’s SEPA Environmental Checklist .

If you or someone in your community would like to learn more about the project, please contact Kristine Cramer, or 206-477-5415 to schedule a briefing.

Sign up for email or text updates

To sign up for text alerts, text KING MERCERSEWER to 468-311 for Mercer Island, and KING ENATAISEWER to 468-311 for Enatai. To sign up for email updates, please visit the public involvement page.


Contact us

Contact Kristine Cramer, community services lead at:


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Project description

With over 400 miles of pipes moving wastewater to one of our award-winning treatment plants, King County WTD works hard to maintain our system. We inspect and monitor our regional system and update plans for needed upgrades.

King County WTD needs to replace sewer pipes that serve areas in North Mercer Island, the southwest portion of Bellevue near Enatai Beach, and the Town of Beaux Arts Village . This pipeline carries wastewater from the North Mercer Island Pump Station to the Sweyolocken Pump Station in Bellevue.

Project area mapView larger version . December 2018


Project design began in 2016 and will be complete in early 2020. Construction is expected to begin in 2020 and extend until 2024.

project timeline View larger version .

Project location


Back to the capital projects overview map .

Related information

Regional Wastewater Services Plan

Local municipalities: