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Lake Hills and NW Lake Sammamish sewer upgrade

The Lake Hills and NW Lake Sammamish Sewer Upgrade Project will upgrade 4.5 miles of sewer pipes serving the growing Redmond and Bellevue area.

Project description

The Lake Hills and NW Lake Sammamish sewer pipe has been serving Redmond and Bellevue for 50 years, carrying wastewater to Brightwater Treatment Plant in Woodinville for treatment. King County is working on a project to upgrade 4.5 miles of this sewer pipe to meet the growing needs of the community. King County will build the new pipe in trails, roads, and parks in Redmond.

Construction on the project is expected to begin in 2026 and may impact your daily routine. When the project is complete, the new pipe will provide sewer service for 50 years or more.

Project update

January 2025

Continuing work in 2025

Starting in January 2025, crews working for King County will conduct surveys in the project area. Crews will drive along the project route and walk along the Sammamish River Trail to remap the corridor and document any changes.

Two construction workers in orange vests using survey equipment next to a road.

What to expect: 

  • Work is anticipated to start the week of January 27 and will last 2-3 days
  • Crews will consist of 2-3 people wearing identifiable gear, like vests and hard hats, and carrying cameras, tripods, and GPS equipment
  • Crews do not anticipate needing to obstruct movement by others traveling through the project area or using the bike path

Continuing fieldwork is part of completing the project’s final design. In addition to survey work, we will also continue securing local, state and federal permits to prepare for the start of construction. To learn more about project updates, you can find our team tabling at local community events this summer. Our first event will be Bike Everywhere Day on May 16. We look forward to seeing you there!

Designing large sewer upgrades take time… Construction now expected to begin in 2027

King County continues to update the design of the sewer upgrade project to meet permitting requirements from the City of Redmond, the City of Bellevue, and several state and federal agencies. Coordination with our partner agencies is necessary to make sure we install the new pipe in the safest way possible, limit impacts and maximize improvements for people and the environment.

Due to a delay in the design and permitting processes, we anticipate construction will begin in 2027. Thank you for your patience while we work hard to finalize our sewer design.

Interested in a project briefing for your community group?

We are happy to meet with you or come to your next community event to share the latest project information and to answer questions you might have as we get closer to construction. Please contact Annie Plumley at 206-263-3203 or aplumley@kingcounty.gov for more information.

Sign up for project text alerts

Be sure to sign up for project updates to stay up-to-date on the latest project information and upcoming events. You can also get updates from your phone. To sign up for text alerts, text KING REDMONDSEWER to 468-311.

Previous project updates

Project location

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