Sammamish Plateau Diversion

Project update

October 23 2025

Thanks so much to everyone who stopped by our King County booth to learn about the work of Department of Natural Resources and Parks (DNRP). Every division in DNRP – including the Wastewater Treatment Division – works together to protect and restore the natural environment for the people, fish, and wildlife of King County. 

We enjoyed the opportunity to raise awareness about the Sammamish Plateau Diversion Project – a project that will build a new pipe to meet future wastewater needs of the local and regional wastewater system in the east Lake Sammamish area. 

As soon as late October and pending permit approval, crews will begin surveying the right-of-way along East Lake Sammamish Parkway. We have a few details about what you can expect below, but will be sending further information once the permit is approved and before the work begins.

Crews will be surveying on East Lake Sammamish Parkway between Northeast Inglewood Hill Road and Northeast 65th Street. This includes marking utilities, and investigating and understanding the location of local, underground utilities.

During this work, you may experience brief delays as crews survey the road. Access to the roadway and trail will be maintained by flaggers. This work is expected to take up to six to eight months, depending on conditions.

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, 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.

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Read our latest project brochure in Español (Spanish), 中文 (Chinese, Simplified), 正體字 (Chinese, Traditional), 日本語 (Japanese), 한국어(Korean), and Русский (Russian).

We welcome you to contact us at any time during the project to talk, ask questions, express concerns, and give feedback and input.