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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 Sammamish Plateau Diversion Project will create new infrastructure to manage some wastewater flows from the East Lake Sammamish area. Currently, wastewater flows from the Sammamish Plateau travel to South Treatment Plant in Renton. When the project is finished, a portion of those flows will travel north to King County’s Brightwater Treatment Plant.
This project will add capacity to serve current and future populations in a busy, growing area.
Project update
July 12, 2024
King County’s Sammamish Plateau Diversion Project team will begin soil and groundwater surveys with drilling equipment later this month. The goal of this work is to obtain samples at key locations along on East Lake Sammamish Parkway.
This work will require temporary single-lane closures on East Lake Sammamish Parkway between Northeast 49th Place and Northeast Inglewood Hill Road during the day. If you live nearby or travel through the area, you can anticipate minor traffic delays.
Work is anticipated to take about two to three weeks to complete, depending on permit and field conditions. We will update this website with more information when the permit and work schedule are finalized.
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
- 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 | 2026-2028 | 2028-2030 |
|---|---|---|
| Alternatives Analysis | Design | Construction |
Project timelines may change due to a number of factors. The Sammamish Plateau Diversion Project is in an early phase. We will provide updates as our work progresses and any schedule changes are needed.