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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 update

July 2026

Tree surveying starts July 6

King County will survey trees in the project area as early as Monday, July 6. Crews will mark trees with tape, as needed.

Read our latest email update for more information.

Meet us at Derby Days on July 25

Stop by to learn more about the project, meet our team, and pick up free items. We hope to see you there!

Construction planned to begin in 2029

We will continue to gather information, work with nearby property owners, and finalize our project designs until we start construction.

Interested in a project briefing for your community group?

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

King County will replace 4.5 miles of sewer pipes in Redmond and Bellevue. These pipes are more than 50 years old. The new pipes will support the growing community. This regional sewer upgrade will keep service safe and reliable for many years in the future.

If you live or work on the northwest side of Lake Sammamish, these sewer pipes serve you every day. The dirty water you make goes into these pipes. Then it travels to Brightwater Treatment Plant near Woodinville! First, the water you send down the drain moves through private pipes. Then, it flows into the local sewer system. The local sewer system connects to King County’s larger regional sewer pipes. These regional pipes deliver dirty water to King County’s regional treatment plants. The treatment plants clean the water and send it safely to Puget Sound. 

Project location