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Sammamish Plateau Diversion
The Sammamish Plateau Diversion Project will build new wastewater infrastructure to serve the growing East Lake Sammamish area.
Project description
The project includes new underground pipes in the East Lake Sammamish area and upgrades to the York Pump Station near Redmond.
This project will help WTD to expand its services and meet future wastewater needs.
Project update
May 2, 2025
The project team continues to conduct field research. We expect to conduct required stream assessments in summer 2025. The map below shows streams that run through the project area.
We want to hear from you - please take our short survey!
King County’s project team wants to get to know you and your community better. By understanding your needs, we can serve you more effectively during the design and construction phases of this project. Please share your feedback with us by completing this survey. We expect that this survey will take about 10 minutes to complete.
We have two different surveys: one for community members and one for local businesses. If you are both a community member and a local business owner in the project area along East Lake Sammamish Parkway Northeast (see map below), please fill out both surveys.
- Community members: publicinput.com/kcwtdsammcomsurvey
- Businesses: publicinput.com/kcwtdsammbussurvey
If you prefer to provide the information in the survey over the phone or by other means, please contact Monica Van der Vieren at 206-477-5502 or monica.vandervieren@kingcounty.gov.
Learn about the latest project update.
We welcome you to contact us at any time during the project to talk, ask questions, express concerns, and give feedback and input.
Previous project updates
- Updates from the Sammamish Plateau Diversion Project, March 2025
- Single lane closures on East Lake Sammamish Parkway scheduled for January 17, January 2025
- Traffic detours for monitoring equipment in East Lake Sammamish Parkway beginning the week of January 13th, January 2025
- Updates and holiday sewer tips from the Sammamish Plateau Diversion Project, December 2024
- Field work update and opportunity to provide input, October 2024
- Schedule update: East Lake Sammamish Parkway single-lane closures are scheduled to start October 10, October 2024
- Work along East Lake Sammamish Parkway starts October 9, October 2024
- Work along East Lake Sammamish Parkway starts next month, September 2024
- Permit approved for East Lake Sammamish Parkway single-lane closures, August 2024
- Upcoming work along East Lake Sammamish Parkway expected to begin later this summer, July 2024
- New schedule for upcoming work along East Lake Sammamish Parkway, July 2024
- East Lake Sammamish Parkway single-lane closures, July 2024
- Field Work coming up this summer on East Lake Sammamish Parkway, May 2024
- King County’s Sammamish Plateau Project looks forward to a busy year, February 2024
- Welcome to the Sammamish Plateau Diversion Project, December 2023
- King County launches the Sammamish Plateau Diversion Project, Fall 2023
Project timeline
| 2023-2025 | 2025-2031 | 2031-2035 |
|---|---|---|
| Pre-design (including alternatives analysis) | Design (including environmental review and permitting) | Construction |
The Sammamish Plateau Diversion Project is in an early phase and project timeline may change during a project due to a number of factors. We will provide updates on our progress and any schedule changes.