North Mercer/Enatai Sewer Upgrade Project
Construction is underway in Mercer Island and Bellevue
Work has begun to upgrade four miles of sewer pipeline across north Mercer Island and southwest Bellevue. In addition to pipeline work, King County will upgrade the North Mercer Pump Station and the City of Mercer Island’s Lift Station 11 at Fruitland Landing. The pipes, installed in the 1970s, are aging and reaching capacity. The sewer upgrade is a big project that will involve years of construction. We expect to complete the project in 2025.
Before major construction starts, crews will be in the area surveying, setting up construction trailers, and preparing work areas for active construction. We will share the construction schedule on our website when it is ready. King County is committed to working with you to minimize impacts whenever possible.
How to use this site: Scroll down this page or use the tabs at the top to jump to more information. The "Construction Activity Map" tab will bring you to a map with links to detailed information about each construction site.
What's Happening Now
You may see any or all of these activities before major construction starts.
Our commitment to you
We were with you during the planning and design phases, and we will be with you every step of the way through construction. This is a big project and it will be disruptive. King County is committed to working with you during construction. Here is what you can expect from us:
- We will provide you with advance notice of construction activities via mail, email, text, web bulletins and project fliers. Sign up .
- We will work with you one-on-one to resolve problems quickly.
- You will be able to reach us through our construction hotline: 425-305-3578.
- We will share updates through our city partners in Mercer Island and Bellevue.
Construction Impacts
We expect that construction will continue for four years.
Construction schedules often change due to weather, staffing, and other unforeseen things like manufacturing delays and a global pandemic. Sign up for email or text alerts on our website to stay informed about the schedule and other construction related items.
The map below is labeled with the construction areas. There are two ways to get more information about that area: either click on the number that is on the map, or scroll down to find your area of interest and click on the button under the description.
You'll find information about:
- What's happening at that location
- What to expect during construction
- How to reach us with concerns or questions
- When and for how long we will be working
- Detour routes, where applicable
- What you'll see when the work is done
When we're done
When work is complete, there will be four miles of new pipe and two upgraded pump stations to keep sewage flowing efficiently for the next fifty years and more.
There will also be improvements that neighbors, park users and passersby will see.
Clockwise from top left: New pavement; North Mercer Pump Station building upgrades and landscaping; a wider I-90 Trail with new planting; shoreline habitat improvements; new trees; ADA compliant crosswalks; and improved fish habitat.
King County is committed to building and operating facilities that benefit our communities and environment.
