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
April 17, 2024
Project-wide Updates: Crews with unique expertise in underwater construction are placing pipe under the East Channel of Lake Washington. Read the news release and watch the video about this construction activity.
Construction activity in Mercer Island*
Area 1. North Mercer Pump Station: Work continues at the North Mercer Pump Station. For more details on what to expect over the next few months, check out our recent notification.
Area 2. North-central Mercer residential streets: Maintenace hole work was completed at the Pump Station. Check out past Area 2 updates here.
Area 3. North Mercer Way: Single-lane traffic along North Mercer Way as early as April 22 for approximately three weeks. Check our more details 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.: Guardrail installation at 90th Pl SE was completed. Check out past Area 5 updates here.
Area 6. NE Mercer Island: As construction activity near East Mercer Way and S.E. 35th Pl. increases, I-90 trail users should continue following our trail detour route off I-90 bridge trail. Drivers, please drive slowly and watch for cyclists on the roadway.
Crews continue installing pipe on S.E. 35th Pl. Starting as early as April 1, S.E. 35th Pl. will be closed between El Dorado Drive and East Mercer Way for approximately one month. Check out our recent notification for more information.
Crews will be moving into Fruitland Landing as early as Wednesday, April 17 to begin construction activities. Initial set-up of the temporary bypass pipe and driveway access ramps is expected to occur April 18-19. Check out our recent notification for more information.
As early as April 10, City of Mercer Island will reduce water pressure across several homes on El Dorado Beach Drive, Briarwood Lane, and S.E. 35th Pl. Check out our recent notification for more information.
As early as April 12 and 13, there will be single lane alternating traffic on Frontage Road. Access to the Mercer Island Boat Launch will be maintained. Check out our recent notification for more information.
Luther Burbank Park: South Parking Lot currently closed due to construction equipment and material storage. For more details, see the latest update.
Construction activity in Bellevue*
Area 7. Enatai Beach Park/Lake Washington’s East Channel: For more details, check out our recent notification.
Expect single lane traffic near Enatai Beach Park as early as April 10. Crews will begin installing electrical conduits. For more details, check out our recent notification.
Area 8. Sweyolocken/Mercer Slough: Work continues near the Sweyolocken Pump Station and the Mercer Slough Boat Launch. The Mercer Slough connector trail is expected to reopen Spring 2024 with a temporary closure as early as June for repaving. Here is the current Mercer Slough trail detour map. Click here for past Area 8 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.
Revised April 1, 2024
Previous general project updates
- 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