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Project update

May 15, 2018

A SEPA Determination of Nonsignificance (DNS) is being issued on May 15, 2018 by the King County Wastewater Treatment Division for the North Mercer/Enatai Interceptor Inspection. View document and provide comments by June 1, 2018. 

A SEPA determination for the entire project will be issued later this year.

Join us at Bike Everywhere Day on May 18! 

King County will host a station for Bike Everywhere Day to share the latest on the North Mercer Enatai Sewer Upgrade Project. Project staff will be available to share information and answer questions about the project.

Friday, May 18
I-90 Trail
Off of NE 34th Street east of Enatai Beach Park
Time: 6 – 9 a.m.


What to expect:

  • Receive trail maps and project materials
  • Learn more about construction impacts on the I-90 Trail
  • Ask questions and sign up for the project listserv

1805_bikersKing County's project team spoke with bicycle commuters at Bike Everywhere Day 2017.

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: