Seattle’s reservoir program was first formulated in the mid-1990s in response to a Washington Department of Health Drinking Water Quality rule. A key driver of this program has always been public health protection and improved water quality. The initial plan was to cover the majority of Seattle reservoirs with floating covers.

The opportunity for new public open space and the additional security advantages led to the approach of undergrounding the remaining in-city reservoirs to be kept in the system. In 2004, the City Council approved the plan to replace Beacon, Myrtle, Maple Leaf, and West Seattle reservoirs at $150 million. The final cost of building the four reservoirs is $133 million. A federal drinking water regulation adopted in 2006 required all uncovered drinking water reservoirs to either be covered or treated to a higher standard. This regulation placed additional priority on eliminating remaining uncovered reservoirs.

Seismic retrofits for covered reservoirs

In March 2011, the project design firm informed SPU about a mistake in seismic calculations, which meant that four covered reservoirs might not comply with building codes. SPU conducted our own seismic analysis and retrofitted the reservoirs to bring them up to code.

Remaining above-ground reservoirs

Seattle has four remaining above-ground reservoirs located in Bitter Lake, Lake Forest Park, Volunteer, and Roosevelt.

The Bitter Lake and Lake Forest Park reservoirs have floating covers, and SPU is in the design phase of a project to replace the floating cover at Late Forest Park.

SPU has decommissioned Volunteer and Roosevelt reservoirs, and is currently conducting a test at both reservoirs. To perform the decommissioning tests, the reservoirs were taken out of service on April 1, 2013. While out of service, Roosevelt Reservoir will be kept drained, while Volunteer Reservoir will remain full with water and continue to be a water feature.