Sammamish Plateau Diversion

Project update

May 21, 2025

The Sammamish Plateau Diversion Project team is continuing field investigations as we work to expand regional wastewater conveyance in the East Lake Sammamish area.

Starting as early as May 21, crews will survey the right-of-way (ROW) in the vicinity of King County’s existing sewer pipes. Surveyors will work on East Lake Sammamish Parkway Northeast and the East Lake Sammamish Trail between 187th Avenue Northeast and just north of Northeast 65th Street (see map below). During this work, surveyors will mark utilities with paint. Access to the roadway and trail will be maintained. Flaggers will direct traffic as needed.

This work is expected to take up to 8 weeks to complete.

What to Expect

• Survey work will take place along the ROW between the hours of 6:30 a.m. and 3:30 p.m., Monday through Friday.
• Drivers may experience brief delays.  
  • Flaggers will be present to direct traffic between 10 a.m. and 3 p.m., Monday through Friday. 
  • No full lane closures are expected, but lane shifts and brief stops may occur. Local and emergency access will be maintained, and school buses will be treated as emergency vehicles to minimize delays. 
• Work will take place up to eight weeks. 
• Traffic signs will be located on East Lake Sammamish Parkway Northeast and the East Lake Sammamish Trail to indicate that flaggers may be present to direct drivers and trail users.
• Sidewalks and the East Lake Sammamish Trail will remain open.

The map on the left below shows the entire project area in blue hatching with a blue inset box that shows the location of the survey work along the ROW. The map on the right shows a zoomed-in view of survey work within the blue inset box. This work is along the ROW on Northeast Inglewood Hill Road and the East Lake Sammamish Trail between 187th Avenue Northeast and just north of Northeast 65th Street.

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.

Read our latest newsletter.

Read our latest newsletter 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.