Seattle Public Utilities (SPU) is replacing its open reservoirs with underground structures that will improve the quality and security of our water supply and provide 76 acres of new open space. The City began installing floating covers at some reservoirs in the late 1990’s. While floating covers improve water quality, they raised concerns about security and visual impacts.
These issues led to the proposal to replace the City’s remaining uncovered reservoirs with safer, more secure underground facilities and use the remaining open space as parks. The City Council approved the plan in 2004, after SPU found the underground reservoir program would cost roughly the same as installing floating covers with improved security measures added. Reservoir Covering