Lake Washington Lake Line Management Plan

Header Image
Lake Washington waterfront park in Bellevue

The City of Bellevue’s "Lake Lines" are a portion of the sewer system located along the shorelines of Lake Washington and Lake Sammamish. Approximately 14.6 miles of the lake lines run along the Lake Washington shoreline, which includes 10 pump stations and eight flush stations. These sewer pipes are either underwater or on land adjacent to the lakes.

Most of the Lake Washington lake lines were constructed in the 1950s and '60s to prevent raw sewage from being directly discharged into the lake. The lake lines are dated, decaying and fragile.

Why lake line management plan is needed

Lake line sewer pipe showing corrosion of interior pipe
In many areas, the aging lake line pipes show signs of significant deterioration, as the photo above shows. 

The city needs to create a lake line management program to effectively assess and manage lake line conditions and maintenance - cleaning, repairing or replacing the pipes. The plan will help ensure we can continue to provide safe and reliable sewer service to the community. Equally important, it will help us protect public health and the delicate Lake Washington ecosystem. 

Deteriorated pipelines pose environmental, service, and financial risks

In 2016, a limited condition assessment showed varying degrees of deterioration of the lake line pipes and interior pipe linings.  Because deteriorated pipes are at higher risk of failure, the condition of the lake lines poses potential hazards to the lake environment, along with financial and service-level risks. 

Photo of lake line visible in Lake Washington
Because of their location within and adjacent to the lake environment, managing the Lake Lines poses unique challenges.
Pipe locations create additional challenges

Because of their location in and adjacent to the lake, managing the lake lines presents multiple challenges, including technical, environmental, operational and financial.

The Lake Washington Sewer Lake Line Management Plan is needed to understand, identify and prioritize key issues present in the system. This will help the city plan and prioritize future repair, replacement and continued condition assessment of the lake lines.     

Project location

This project is located in Lake Washington adjacent to the waterfronts of the following areas (identified on map below):

  • Bellevue
  • Medina
  • Hunts Point
  • Yarrow Point
  • Beaux Arts Village
  • Small portion of unincorporated King County
Lake Washington Sewer Lake Lines

Project timeline

Development of the management plan began in early 2020 and is anticipated to be completed in mid-2022.

Public engagement

The city will use multiple channels to communicate important information and updates throughout the project, including this project website, mailed notices, online public meetings, and possible in-person meetings (pending COVID-19 conditions).

Please subscribe to the project website for updates and look for a mailed notice soon. We expect to hold a public workshop to help communicate information on the project in the near future.

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