Lake Washington Lake Line Management Plan

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

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. 

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.