North Mercer Island/Enatai sewer upgrade

General project updates

October 6, 2025

Project-wide updates

Construction is underway across north Mercer Island and southwest Bellevue. To keep everyone safe, follow all instructions from crews and signage and use caution as you travel through work areas.

King County’s contractor has been approved to continue working extended Saturday hours from 7 a.m. to 7 p.m. in all project areas across north Mercer Island. These extended hours began in June 2024 and are now approved through December 27, 2025. For more information, check out our August project-wide notification.

Please note that the texting option on our hotline is not currently available. To connect with us, please call our hotline at 425-305-3578 or email NMESewer@kingcounty.gov.

Construction activity in Mercer Island*

Area 1. North Mercer Pump Station: Crews continue work to upgrade the pump station, including work on the pump station building, the generator building and testing newly installed systems.

Area 2. North-central Mercer residential streets: Final paving and restoration activities on Southeast 22nd Street, Southeast 22nd Place, 78th Avenue Southeast, and Southeast 24th Street has been postponed. Once the schedule is finalized, we will send a notice with more details and update the project website. For more information, please review our most recent August Area 2 notification.

Area 3. North Mercer Way: As early as October 6, King County's contractor will close 81st Avenue Southeast as crews begin pipe adjustment work. The road will remain closed to through-traffic through late October so crews can complete the work safely and efficiently. Please follow instructions from flaggers, traffic control, and signage while traveling through this work area. For more information, please review our October Area 2 notification.

Area 4. I-90 Trail: The I-90 Trail between Island Crest Way and SE 35th Street is now open for trail users. Crews may occasionally be on site to access maintenance holes for cleaning or testing.

The I-90 Trail remains closed between Southeast 35th Street/North Mercer Way and Southeast 35th Place/East Mercer Way for sewer construction in the area. Trail users should follow the posted detour route:

• Trail detour map between S.E. 35th St and S.E. 35th Pl. This takes trail users on East Mercer Way, Southeast 36th Street, and North Mercer Way, before connecting back to the I-90 Trail. Drivers, please drive slowly and watch for cyclists on the roadway.

For more information, check past Area 4 updates.

Area 5. 90th Pl S.E.: Paving on 90th Pl S.E. is complete. Crews continue work on the odor control structure in the cul-de-sac at the top of 90th Pl S.E. For more information, check past Area 5 updates.

Area 6. NE Mercer Island:

Fruitland Landing: As early as October 7, crews will grind the roadway on 97th Avenue Southeast in preparation for final paving. Grinding is expected to be completed in one day. Paving will begin as early as October 16 and is expected to take one day to complete. For more information, please review our recent Area 6 notification.

S.E. 35th Pl: As early as October 7, crews will grind the roadway on Southeast 35th Place and Frontage Road in preparation for final paving. Grinding is expected to be completed in one day. Paving will begin as early as October 16 and is expected to take one day to complete. For more information, please review our recent Area 6 notification.

Mercer Island Boat Launch: Crews have completed work to install a sidewalk ramp on the east side of Frontage Road near the boat launch. The parking lot is open for community use.

For more information, check past Area 6 updates.

Luther Burbank Park: King County’s contractor has moved construction equipment out of the back half of the South Parking Lot at Luther Burbank Park. The full parking lot is open for community use. 

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Construction activity in Bellevue*

Area 7. Enatai Beach Park/Lake Washington’s East Channel:

East Channel: A four-person crew on a boat will survey the East Channel as early as September 5. This crew will also conduct elevation and drone surveys along the shorelines at the Mercer Island Boat Launch and Enatai Beach Park. This work is expected to be completed within two days. For more information, check out past Area 7 updates.

Enatai Beach Park: Crews continue to work on pipes and structures near the swim beach and under the I-90 bridge. Both parking lots as well as the swim beach, dock, and playground are all open for community use. For more information, check out past Area 7 updates.

Area 8. Sweyolocken/Mercer Slough: The Sweyolocken boat launch and Mercer Slough connector trail is open for community use. Crews are in the area to work on structures near the Sweyolocken Pump Station. For more information, check out past Area 8 updates.

* Construction schedules can change based on factors such as site conditions, weather, and material availability. Please check this website for 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.

Map current as of February 1, 2025