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
September 5, 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 are working 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 activity in Mercer Island*
Area 1. North Mercer Pump Station: Crews continue to upgrade the existing pump station. There may be intermittent single-lane traffic near the pump station for deliveries. For more information, check out the June Area 1 notification.
Area 2. North-central Mercer residential streets: Pipe repair work continues on 78th Avenue Southeast, Southeast 24th Street, and 81st Avenue Southeast. Expect periodic, single-lane traffic with flaggers until the work is complete.
Please use caution when traveling through the work area and follow all signage and directions from the crew. For more information, check out the August 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 is closed between Southeast 26th Street and Shorewood Drive for pipe testing and restoration. Paving for this section of trail is planned to begin as early as mid-September. It is expected to reopen later this fall once testing, paving, and restoration are complete. For more information, check out the August Area 4 notification.
The I-90 trail remains closed between Southeast 35th Street and Southeast 35th Place for pipe installation. Trail users should follow posted detour routes:
- Trail detour map between S.E. 26th St and Shorewood Dr. This takes trail users along North Mercer Way, before connecting back to the I-90 trail.
- 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 Shorewood Drive and the lower section of 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:
Fruitland Landing: Fruitland Landing park is closed while crews upgrade Lift Station 11. Crews have installed new pipe on 97th Ave S.E. south of S.E. 34th St. Crews are preparing to reline the existing pipe on 97th Ave S.E. north of S.E. 34th St. Paving the south end of 97th Ave S.E. near the I-90 trail is planned for as early as mid-September.
S.E. 35th Pl: Crews continue to install pipe and structures on S.E. 35th Pl. Most residents will continue to access their homes from the temporary access road off Frontage Road. Paving on S.E. 35th Pl is planned to occur as early as mid-September. For more information, check out the August Area 6 notification.
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 restored the Mercer Island shoreline in spring 2024. Construction equipment moved out of the parking lot in June 2024, and the parking lot is fully reopen for public use.
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.
Crews are preparing 108th Ave. S.E. near S.E. 34th St for final paving. Expect flaggers, single-lane traffic, and detours in this area through September. The intersection at 108th Ave S.E. and S.E. 34th St will be closed from approximately 9/12 – 9/17 and 9/23 – 9/25 for concrete removal and paving. When the intersection is closed, there will be a detour around the work area. Please drive carefully and follow all signage and instructions from crews when traveling through the area.
Area 8. Sweyolocken/Mercer Slough: The Sweyolocken boat launch and Mercer Slough connector trail is open for community use. Paving the road to the boat launch is expected to begin as early as mid-September. For more information, check out the July Area 8 notification.
* 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 September 1, 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