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
November 17, 2023
Project-wide Updates: Check out our Spring Newsletter for an overview of this year’s progress and upcoming work. Our newsletter is available in English, Español (Spanish), 中文 (Chinese, Simplified), and 正體字 (Chinese, Traditional). See the newsletter here for more.
Construction activity in Mercer Island*
Area 1. North Mercer Pump Station: Work continues at the North Mercer Pump Station. Click here for past updates.
Area 2. North-central Mercer residential streets: Crews begin final restoration in this area. Click here for past updates.
Area 3. North Mercer Way: Striping and repaving was completed along N. Mercer Way. Click here for past updates.
Area 4. I-90 Trail: The I-90 trail between 84th Avenue Southeast and Shorewood Drive is currently closed. For more information, see the trail closure update and tree removal update. See the updated pedestrian detour map.
Area 5. 90th Pl S.E.: Paving and restoration begins on October 5 on 90th Place Southeast. For more information, see the latest update.
Area 6. NE Mercer Island: I-90 Trail closing between North Mercer Way and S.E. 35th Place as early as Oct. 23. For more details, check out our recent notification.
Luther Burbank Park: Construction equipment and material storage coming to South Parking Lot as early as October 2. For more details, see the latest update.
Construction activity in Bellevue*
Area 7. Enatai Beach Park/Lake Washington’s East Channel: Nighttime work in the East Channel begins as early as November 14 through November 30. For more information, see the latest update.
Area 8. Sweyolocken Pump Station: Work continues near the Sweyolocken Pump Station. The Mercer Slough connector trail is expected to remain closed through Winter 2023. See the I-90 trail bike and pedestrian detour map. Click here for past updates.
Revised September 1, 2023
*Please note that construction schedules often change due to weather, staffing, and other unforeseen things. Dates on email notices may differ from the dates posted on the web.
Previous general project updates
- 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