Shrinking Snowpack: The West's Natural Reservoir Is Melting
Mountain snow is the West's largest reservoir. As warming shifts snow to rain and melts it earlier, the timing and reliability of water supply are unraveling.
Across the western United States, mountain snowpack acts as a giant natural reservoir, storing winter precipitation and releasing it slowly through spring and summer when demand peaks. Cities and farms are engineered around that timing.
Warming temperatures are disrupting it: more precipitation falls as rain instead of snow, snow melts earlier, and peak runoff arrives weeks ahead of when it's needed. Even in normal-precipitation years, 'snow drought' can leave reservoirs short.
The shift forces utilities to rethink reservoir operations and lean harder on groundwater, reuse, and storage — because the free storage that snowpack once provided can no longer be counted on.
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States facing this
Colorado
Utah
California
Washington
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