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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

May 2024

Join us for Bike Everywhere Day on May 17!

We are hosting a booth for Bike Everywhere Day on Friday, May 17 from 6-10 a.m. Stop by our booth to learn more about the project and meet a few members from our team. You’ll find our booth located along the Sammamish River Trail near the entrance to Marymoor Park. We hope to see you there! 

The Bike Everywhere booth is located along the Sammamish River Trail near the entrance to Marymoor Park, west of the Sammamish River.

Designing large sewer upgrades take time… Construction now expected to begin in 2026

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 2026. Thank you for your patience while we work hard to finalize our sewer design.

Detour update

One highlight from this year is that we were able to share information about our updated Sammamish River Trail (SRT) detour. When construction begins, King County’s contractor will intermittently close sections of the SRT between NE 85 Street and NE 51 Street and will detour traffic accordingly. This view shows a section of the planned detour between NE Leary Way and SR 520. A barrier will separate northbound vehicle traffic from bikes traveling southbound. The shared use path will be for northbound bikes and for trail users.

This view shows a section of the detour between NE Leary Way and SR 520. A barrier will separate northbound vehicle traffic from bikes traveling southbound. The shared use path will be for northbound bikes and for trail users.

To see how the detour will help safely organize vehicle traffic and trail-users along West Lake Sammamish Parkway between NE Leary Way and NE Marymoor Way, view the detour update information from our most recent listserv. Be sure to sign up for our listserv to receive project updates as we finalize 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 Pfeifer at 206-263-3203 or amurrillpfeifer@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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