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Coal Creek sewer upgrade

The Coal Creek Sewer Upgrade Project will install new sewer pipes to carry more wastewater and meet the growing needs of Bellevue and Newcastle.

Project description

The Coal Creek Sewer Upgrade Project will upgrade a regional sewer line that serves Bellevue and Newcastle. Built between 1966 and 1991, the existing pipeline is nearing its maximum capacity and needs to be upgraded to carry more wastewater and meet the growing needs of the community.

Once installed, the new sewer pipe will serve the area for another 50 years or more.

Project update

April 2025

Coal Creek project awarded Salmon-Safe Certification

Learn about Salmon-Safe Certification, project updates and two local events to meet the project’s Community Services team in person in April.

King County’s major sewer upgrade in Bellevue is the first project of its kind to earn Salmon-Safe certification, simultaneously modernizing infrastructure and improving habitat

One of the nation’s leading eco-labels, Salmon-Safe, has awarded its first ever certification for a wastewater infrastructure project to King County’s Coal Creek Sewer Upgrade in Bellevue.

View full report and video.

Construction starting this year!

A new clean water project is about to hit the ground running! King County has awarded the construction contract for the Coal Creek Sewer Upgrade Project. The contractor is anticipated to begin work as early as the first quarter of 2025. We are currently working with the contractor on an approved project schedule. When that schedule is available, we will share information with the public and begin outreach to share what we see ahead for the next few years.

Sign up for the project email list to get updates, learn about construction, and find outreach activities that you can participate in!

Interested in a project briefing for your community group?

We are available meet with you or come to your next community event. The project team share the latest project information and talk about what will happen over the next several years of construction. Please contact Frances Kuo 206-263-9237 or CoalCreekProject@kingcounty.gov

Previous project updates

Project location

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