North Mercer Island/Enatai sewer upgrade
The North Mercer Island/Enatai Sewer Upgrade Project will replace aging pipes serving areas in North Mercer Island and Bellevue near Enatai Beach, and the Town of Beaux Arts Village.
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
October 31, 2024
Project-wide updates
Check out our 2024 newsletter for an overview of this year’s progress and upcoming work. This newsletter is available in English, Español (Spanish), 中文 (Chinese, Simplified), and 正體字 (Chinese, Traditional).
Read the newsletter here to learn more
Crews have been approved to work extended Saturday work hours from 7 am to 7 pm in parts of the project area. Check out our June notification for more information.
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.
Construction activity in Mercer Island*
Area 1. North Mercer Pump Station: Crews have completed work to remove the old water service main on S.E. 22nd Street.
Area 2. North-central Mercer residential streets: Crews are doing pipe repair work on 78th Avenue Southeast between Southeast 22nd Place and Southeast 24th Street doing pipe repair work. For more information about construction impacts and detour routes, check out the October 18, 2024 Area 2 notification.
Area 3. North Mercer Way: Crews installed pipe and paved North Mercer Way in 2023 and installed accessible curb ramps in spring 2024. For more information, check out past Area 3 updates.
Area 4. I-90 Trail: The I-90 trail between Southeast 26th Street and Shorewood Drive is now open!
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.
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 structures 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:
S.E. 36th St near City Hall: Crews completed utility potholing work on Southeast 36th Street near City Hall.
Fruitland Landing: Fruitland Landing park is closed while crews upgrade Lift Station 11. Crews are testing the new pipe installed on 97th Ave S.E. south of S.E. 34th St. For more information, check out the October 2024 Area 6 notice.
S.E. 35th Pl: Crews are installing an air vent line in the roadway on East Mercer Way at S.E. 35th Pl. Traffic control currently in place is expected to continue through early November. For more information, check out the Area 6 notice.
I-90 trail: As construction continues on northeast Mercer Island, I-90 trail users should follow posted detour routes off the I-90 bridge trail. This takes trail users on East Mercer Way, Southeast 36th Street, and North Mercer Way. Trail users will then be able to connect back onto the I-90 trail. Drivers, please drive slowly and watch for cyclists on the roadway.
Mercer Island Boat Launch: Crews are installing a sidewalk ramp on the east side of Frontage Road near the boat launch. Expect single-lane traffic on the road to the boat launch while crews complete this work. The boat launch will remain open.
For more information, check past Area 6 updates.
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: Crews began restoring the shoreline along Enatai Beach Park under the I-90 bridge in late July. Crews continue to work on pipes and structures near the swim beach and under the I-90 bridge. For more information, check out the July Area 7 notification.
Area 8. Sweyolocken/Mercer Slough: The Sweyolocken boat launch and Mercer Slough connector trail is open for community use. Paving and restoration activities are complete. 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
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 October 22, 2024
Previous general project updates
- Hard work and big progress in 2023, and more to come in 2024!, SPRING 2024
- Newsletter - Sewer construction has been progressing for a year, Spring 2023
- Updated Bike Detour Map available, February 2023
- Enatai Siphon pipe installation is complete! December 19, 2022
- See you at the Mercer Island Farmers Market! August 17, 2022
- Construction schedules often change – check our website for the most up to date information! August 12, 2022
- Summer newsletter available online, check your mailbox or nearby flyer box! July 26, 2022
- Newsletter - Major sewer construction activities continue this summer and fall in Mercer Island and Bellevue, July 2022
- Watch out! Cycling in a construction zone is dangerous! Proceed with caution to keep us all safe! July 22, 2022
- The construction hotline is back in service; meet us at the Mercer Island Farmers Market this weekend! June 14, 2022
- The North Mercer Island/Enatai construction hotline is down. Please use our temporary hotline number. June 9, 2022
- Construction work on the I-90 trail will begin as early as June 8, June 2, 2022
- Surveying continues/utility locates beginning in May, May 4, 2022
- Construction equipment and activity coming to Mercer Island Boat Launch, April 22, 2022
- Visit our pre-construction online StoryMap, April 6, 2022
- Sewer construction starts this spring! March 2022
- Sewer construction starting soon! March 2, 2022
- Newsletter - Sewer construction starts this spring! March 2022
- Newsletter - Construction Ahead, April 2021
- Construction Reference Guide, April 2021
- Utility work on SE 35th Place between E. Mercer Way and Briarwood Lane planned for early February, January 25, 2021
- Utility work on 78th Avenue Southeast planned for late December 2020, December 14, 2020
- Utility work on 90th Place Southeast planned for late November 2020, November 23, 2020
- Field investigations starting as early as April 22 near Mercer Island Boat Launch and Enatai Beach Park, April 21, 2020
- Field investigations near Sweyolocken Pump Station starting as early as January 9, January 7, 2020
- Tree and site survey along I-90 Trail and North Mercer Way starting as early as December 9, December 6, 2019
- Fieldwork at Luther Burbank Park starting as early as May 20, May 17, 2019
- Fieldwork at Mercer Island Boat Launch starting as early as May 20, May 17, 2019
- Construction and restoration on the I-90 Trail, Spring 2019
- Join us at Bike Everywhere Day on May 17! May 10, 2019
- Tree survey near I-90 Trail and North Mercer Pump Station starting as early as April 22, April 19, 2019
- Newsletter, March 2019
- Field investigations starting as early as March 4 in Enatai Beach Park and Sweyolocken Pump Station, March 1, 2019
- Utility locates, potholing, and surveying in North Mercer Island beginning as early as January 3, December 28, 2018
- Field investigations starting as early as December 3 near Bellevue shoreline, Enatai Beach Park and Sweyolocken Pump Station, November 20, 2018
- Tree survey work beginning November 5, October 30, 2018
- In-water fieldwork along Bellevue shoreline starting July 18, July 16, 2018
- Join us at Bike Everywhere Day on May 18!
- Field investigations starting as early as April 16 on Mercer Island, April 10, 2018
- Field investigations starting as early as April 12 in Enatai Beach Park and Mercer Slough, April 10, 2018
- Field investigations next to I-90 Trail and on SE 35th Place starting on Wednesday, April 4, April 2, 2018
- The online open house is live! Stop by to review the detailed sewer upgrade route, March 1, 2018
- Field investigations starting as early as January 24 in Mercer Island and Bellevue, January 22, 2018
- Survey work on Mercer Island January 8-12; Expect delays along North Mercer Way, January 3, 2018
- Potholing to locate underground utilities is underway. Expect delays along North Mercer Way. December 15, 2017
- Fact sheet: Keeping sewage flowing during construction (Grinder Pumps), November 2017
- Sewer route details come into focus, July 2017
- Survey notification, July 2017
- In-water survey work near Enatai Beach Park and Mercer Island Boat Launch starting June 21, June 15, 2017
- Fact sheet: Installing King County’s new sewer pipeline in North Mercer Island/Enatai, April 2017
- Newsletter, January 2017
- Post card: Join us for an upcoming community meeting (January 25 and 26), January 11, 2017
- Soil sampling resumes on Mercer Island starting November 30, November 23, 2016
- Final alignment decision expected by year’s end, November 15, 2016
- Soil sampling on 96th and 97th avenues southeast starting as early as Tuesday, November 1, October 28, 2016
- Soil sampling starting as early as Thursday, October 27, October 21, 2016
- Survey work begins on Mercer Island September 19, September 16, 2016
- Early design for King County’s North Mercer Island and Enatai Sewer Upgrade Project, August 2016
- Field investigations move into the East Channel week of August 8, August 3, 2016
- Field investigation update and changing of the guard, August 1, 2016
- Geotechnical work to begin in Bellevue, Week of July 11, 2016, July 5, 2016
- King County begins field investigations at North Mercer Island and Southwest Bellevue in June 2016, June 1, 2016
- North Mercer Island/Enatai sewer upgrade newsletter, Summer 2015
- King County continues field investigations in your neighborhood April 20, April 15, 2015
- King County continues field investigations in your neighborhood April 13, April 8, 2015