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Project description 

King County is replacing sewer pipes that serve areas in North Mercer Island, the southwest portion of Bellevue near Enatai Beach Park, and the Town of Beaux Arts Village. This pipeline carries wastewater from the North Mercer Island Pump Station to the Sweyolocken Pump Station in Bellevue. Once installed, the new pipes will provide sewer service for 50 years or more. To learn more about the project overall, including what we are building, construction information, and what to expect, view our StoryMap.

To meet community needs, we broke the project up into 8 project areas, shown on the map. We provide updates about specific areas depending on where work is taking place.


General project updates

May 17, 2024

Construction activity in Mercer Island* 

Area 1. North Mercer Pump Station: Work continues at the North Mercer Pump Station. Check out past Area 1 updates here.  

Area 2. North-central Mercer residential streets: Check out past Area 2 updates here.

Area 3. North Mercer Way: Check our past Area 3 updates here.

Area 4. I-90 Trail: The I-90 trail is closed for pipe installation between Southeast 26th Street and Shorewood Drive and between Southeast 35th Street and Southeast 35th Place. For more information please review our recent Area 4 updates.

Click here for the trail detour map between S.E. 26th St and Shorewood Dr.

Click here for the trail detour map between S.E. 35th St and S.E. 35th Pl.

Area 5. 90th Pl S.E.: Final paving on lower section of 90th Place Southeast and 89th Place Southeast planned for May 28 and 29. Check out our recent notification for more information.

Area 6. NE Mercer Island:

As construction activity near East Mercer Way and S.E. 35th Pl. continues, I-90 trail users should continue following our trail detour route off the I-90 bridge trail. Drivers, please drive slowly and watch for cyclists on the roadway.

Crews continue installing pipe on S.E. 35th Pl. Detours on S.E. 35th Pl expected to remain in place through June. Check out our recent notification for more information

Luther Burbank Park: Construction equipment moved out of the South Parking Lot on May 15. This parking lot is now fully reopen for public use.  

Construction activity in Bellevue*

Area 7. Enatai Beach Park/Lake Washington’s East Channel: Parking and pathways reopen for public use for the summer as construction continues at Enatai Beach Park. For more details, check out our recent notification.

Area 8. Sweyolocken/Mercer Slough: The Sweyolocken boat launch and Mercer Slough connector trail is now open for community use!

Construction continues near the Sweyolocken Pump Station, boat launch, and trail. There may be intermittent closures and short delays for final paving and restoration activities. We will share more details about impacts. Click here for past Area 8 updates

Construction status

Click for larger view.

This map is updated as construction progresses across north Mercer Island and southwest Bellevue. It shows areas of planned construction, active construction, and post-construction restoration.

If you need this map in another format, please leave a voicemail on the project hotline at 425-305-3578 or call TTY Relay 7-1-1. Reasonable accommodations are available to you for free.

Revised April 1, 2024

Previous general project updates

Project location