Bitter Lake Reservoir Improvement Project

Project description

The existing floating cover at Bitter Lake Reservoir (BLR) is reaching the end of its service life. SPU plans to replace the floating cover and existing 21-million-gallon (mg) reservoir with a new partially buried 21 mg concrete tank. When the project is complete in 2028, it will also include additional open space that will be developed into a park by Seattle Parks and Recreation.

The Bitter Lake Reservoir Improvements project will:

  • Demolish and remove the existing reservoir and associated facilities
  • Construct a new partially buried circular 21-million-gallon reservoir and associated facilities
  • Provide site improvements, including grading, landscaping, and stormwater upgrades
  • Move the current fence line closer to the reservoir and install a more neighborhood-friendly fence
  • Continue to provide protection for the delivery of clean, safe, and reliable drinking water


The reservoir is located on a 13.3-acre property located southwest of the intersection of Linden Ave N and N 143rd St in North Seattle. About four acres of the site currently includes open space, a playground, and a P-path for public use.

What's happening now?

SPU investigated four possible reservoir improvements options that would protect and preserve the water service and quality that the reservoir provides. The options evaluated included:

  • Option 1: Replace the reservoir’s existing floating cover with another similar floating cover.

  • Option 2:Replace the reservoir’s existing floating cover with a new low-slope aluminum roof.

  • Option 3: Replace the existing reservoir with a new partially buried 21-million-gallon circular concrete tank.

  • Option 4: Replace the existing reservoir with a new fully buried 21-million-gallon rectangular concrete tank.

Based on costs and the opportunity for Seattle Parks and Recreation to upgrade Bitter Lake Reservoir Park and provide additional open space in the Bitter Lake neighborhood, SPU selected Option 3 in 2021.

The project team has started designing the new reservoir. Later this year, SPU will begin reaching out to the community to share project information and gather feedback about how community members would like to be engaged and kept informed about this project.

Community benefits

This project is part of SPU’s regional drinking water system. When construction is complete, the new reservoir will provide protection from sunlight, dirt, leaves, and other debris to help preserve water service and quality for years to come. The project will provide additional open space for the community.

Anticipated impacts

During construction, you can expect:

  • Crews are expected to work 8-10 hour days Monday through Saturday to ensure most of the work can be performed during the dry weather season
  • General construction traffic and noise during working hours
  • The construction work will take place within the reservoir site
  • No road closures are expected, but there will be increased construction traffic in the area
  • The walking path that goes around the reservoir site will generally remain open and accessible
  • Nearby roadways and paths may experience brief temporary delays as the construction entrance is rebuilt and to accommodate equipment and materials moving in and out of the construction site
  • Although the project will take place near Horizon View Park, there are no anticipated impacts for park visitors
  • This work will not impact water services to homes and businesses

Community engagement

SPU is committed to providing timely information and updates on project activities. Updates may be available in multiple formats: the website, emails, mailings, drop-in sessions, briefings, and/or public meetings. There will be several opportunities for the public to engage and provide feedback throughout the project. Check back for more information about upcoming opportunities to get engaged. If you are interested in receiving updates, please subscribe to the project email list.


  • Design
  • Permitting
  • Community Engagement


  • Construction
  • Community Engagement

Project Fact Sheet coming soon.

Public Utilities

Andrew Lee, General Manager and CEO
Address: 700 5th Avenue, Suite 4900, Seattle, WA, 98104
Mailing Address: PO Box 34018, Seattle, WA, 98124-5177
Phone: (206) 684-3000

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Seattle Public Utilities (SPU) is comprised of three major direct-service providing utilities: the Water Utility, the Drainage and Wastewater Utility, and the Solid Waste Utility.