Skip to main content
King County logo

Project update

February 16, 2018

Progress continues: Learn more at an upcoming walk-and-talk or online open house

In 2017, King County’s project team refined the pipe location for the project, contacted property owners from whom we need property rights to build the pipe, and identified some constraints for construction. In 2018, we’ll be completing environmental review and developing construction specifics, including early construction timeline estimates and methods. For a detailed look at what we accomplished in 2017 and what’s coming up this year, check out the latest project update .

map of pipe alignment

Upcoming opportunities to learn more:

  • Online open house: March 1 – March 31
    Visit our online open house in March to review the latest project information and maps, ask questions and let us know how we can be a good neighbor during construction. Check back to our website on March 1st to access the online open house.
  • Mercer Island walk-and-talks: Saturday, March 3, 2018
    Our team will be walking residential streets on Mercer Island to discuss the detailed route with neighbors and answer questions about what to expect during construction. Additional information about this event, including times and meeting locations, is available on our meeting calendar.

Field investigations continue in Mercer Island and Bellevue

King County Wastewater Treatment Division is continuing field investigations to inform design of a sewer upgrade project in Mercer Island and Bellevue. Crews began taking soil sampling, ground surveys and potholing in late January and will continue through March.

Crews taking soil samples, ground surveys and potholing.

For additional information, see the latest project update .

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:


 Feedback form

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.

1701_NME-final-pipeline-route_700View larger version. July 2017


Project design will begin in 2016. Construction is expected to begin in 2019 and extend until 2022.

Project TimelineClick to view larger version .

Project location


Back to the capital projects overview map .

Related information

Regional Wastewater Services Plan

Local municipalities: