Reservoir Covering

What & Why

Seattle Public Utilities (SPU) has replaced six of its open reservoirs with underground structures that will improve the quality and security of our water supply. Following SPU’s reservoir covering projects, Seattle Parks and Recreation Department constructed recreational open space improvements over the covered reservoirs. The reservoir covering program provided 90 acres of new open space. Reservoirs that have been replaced with underground structures and new open space areas include Magnolia (1995), Lincoln (2004), Myrtle (2008), Beacon (2009), West Seattle (2010), and Maple Leaf (2012).

Seismic Retrofits

Seismic reviews of the West Seattle, Maple Leaf, Myrtle and Beacon Reservoirs indicated that they all required a retrofit to the floor slab perimeter. No new excavation work was needed for these retrofits. The work was done inside the reservoirs via existing access hatches. Utility rates were unaffected by the project.

What’s happening now?

Lake Forest Park Reservoir Cover Replacement

SPU is currently in the design phase of a project that will replace the floating cover over the Lake Forest Park Reservoir. To learn more and receive email updates about this project, please contact Andrew Karch at

Roosevelt and Volunteer Decommissioning Test

SPU has decommissioned the Volunteer and Roosevelt Reservoirs to study the impact the out-of-service facilities have on Seattle’s overall drinking water system, make evaluations, and determine whether these reservoirs can be permanently taken out of service.

Drinking Water System Seismic Study

Along with the decommissioning test, in 2018 SPU continues to conduct a seismic evaluation to look at how the City’s entire drinking water distribution system would perform in a large earthquake. Water storage for both drinking water and fire flow is an important aspect of this study.

The potential water storage in both Roosevelt and Volunteer Reservoirs in a post-earthquake scenario is being considered in the seismic study.

When the study is concluded, SPU will have the critical information it needs to make recommendations about the reservoirs. These recommendations will include whether the reservoirs are needed to provide emergency water storage or if they can be declared surplus properties and no longer a part of the City’s drinking water system.

If SPU were to proceed with property surplus, the City of Seattle would conduct a thorough process to determine the best future use of the property. This process would include many opportunities for public involvement and feedback.

Until the seismic study is complete and recommendations are made about the reservoirs, it is important to note that SPU is not conducting any community planning activities to identify future use(s) of the properties. 

If you would like to be notified when the study is complete and recommendations about Roosevelt and Volunteer Reservoirs are made, please contact the SPU project manager to be added to our email distribution list:

Contact Matt Orr at or 206-733-9169