The mystery of missing water from mountain sources

By Corydon Ireland, Staff Writer, Pacific Northwest National Laboratory

Sublimation of Snow (SOS) Project team members gather at the Rocky Mountain Biological Laboratory in Gothic, Colorado, during the project’s intensive operational period in January 2023. Top row, L-R: Emilio Mateo (AGCI), Ethan Gutmann (NCAR), Danny Hogan (UW), Antonio Vigil (NCAR), Will Nicewonger (NCAR), Eli Schwat (UW). Bottom L-R: Jessica Lundquist (UW), Julie Vano (AGCI), Elise Osenga (AGCI) Photo: Emilio Mateo

A University of Washington project, aided by the Department of Energy’s Atmospheric Radiation Measurement (ARM) user facility, leverages a rare confluence of collaborators to study snow sublimation.

On the westward side of the Rocky Mountains, the Upper Colorado River Basin has historically been a wintertime storage bin for snowpack, the compressed remnants of months of falling snow. As the snowpack melts, the resulting runoff joins water sources from other mountain watersheds and fills the coffers of streams and rivers fanning out into the Western United States.

About 40 million Americans in seven states depend on that water for drinking, hydropower, and agriculture.

But there’s a catch.

Not all the snowpack melts to become usable water. In the spring of 2021, for example, snowpack in this mountain reservoir of the Colorado River measured at about 80% of historical averages. But the water that flowed out of the basin was only about 25% of what was expected.

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