Climate change has likely resulted in diminishing snowmelt even during years of average snowpack, with long-range implications for Western water supplies, Arizona's top water official told a Senate hearing Oct. 6.
Tom Buschatzke, director of the Arizona Department of Water Resources, said the phenomenon of low runoff in average snow years "is something of huge concern to us moving forward." He said further measures to protect the elevations of Lake Mead and Lake Powell will be necessary, including greater water efficiency and increased use of reclaimed water.
The infrastructure bill signed into law Nov. 15 contains $8.3 billion for Western water projects, including $3.2 billion for rehabilitating and replacing aging Bureau of Reclamation facilities; $1.2 billion for storage and conveyance; $1 billion for water recycling and reuse; and $500 million for dam safety.
Buschatzke said in his written testimony that the region has "seen several years in which runoff is significantly lower than snowpack."
His testimony was presented at a hearing on Western drought impacts held by the Senate Energy and Natural Resources Committee's Water and Power Subcommittee.
In response to questions from subcommittee chairman Sen. Mark Kelly (D-Ariz.), Buschatzke said low snowmelt in average years "is a prime example of what climate change is doing. It is hotter. It is drier, and the snow either sublimates or does not run off into the river. It soaks into the ground." Sublimation refers to snow evaporating, bypassing the liquid phase.
Buschatzke added that snowmelt is beginning earlier in the year and spring plant growth is taking place earlier, consuming meltwater.
In other testimony, Tanya Trujillo, the Interior Department's assistant secretary for water and science, said updated five-year projections for the Colorado River show "a continued elevated risk of Lake Powell and Lake Mead declining to critically low elevations, including the potential of Lake Powell falling below minimum power pool as early as July 2022." The power plant at Glen Canyon Dam has a total nameplate capacity of 1,021.2 MW.
Kelly said Lake Mead is now at 35 percent of capacity, the lowest since the reservoir was filled, and Lake Powell is at 30 percent. "They are the poster children of Western drought," he said.