Smaller snowpack may be the new normal
Facing a drier future, water managers turn to science to adapt
The good news: Colorado’s snowpack is normal.
The bad news: Normal isn’t what it used to be.
Snowpack in the Colorado River Basin — which includes Eagle County — is 104% of normal even though March was a relatively dry month. Colorado’s statewide snowpack is 99% of normal, says the Natural Resources Conservation Service’s monthly report.
But normal is changing as the climate changes, and the Upper Colorado River Basin appears to be in the bullseye. Colorado River District Deputy Chief Engineer Dave Kanzer and National Snow and Ice Data Center researcher Jeff Deems discussed what that new normal looks like in a recent webinar.
Temperatures rising, snowpack falling
Since the early 1990s, temperature increases across the Colorado River District’s 15 Western Slope counties range from 2 degrees in Summit County to more than 4 degrees in Mesa, Montrose, Ouray and Rio Blanco counties, according to data from the National Oceanic and Atmospheric Administration.
That could mean a significant drop in the snowpack that provides much of the water for the southwestern United States.
“This is a problem for us because we rely on the snowpack … and warming reduces snowpack,” Deems said.
That could mean:
- More precipitation falling as rain instead of snow
- Earlier spring snowmelt
- More snow directly evaporating into the atmosphere instead of melting into streams
- A longer growing season that has plants taking up more water
For every degree of warming the annual runoff drops an estimated 3% to 4%, Deems said.
That’s about double the amount of water Las Vegas uses in a year, and Los Angeles uses in 18 months.
Substantial snowmelt has already started, and that snowmelt is being absorbed into dry soil, which means this summer’s stream flows are forecast to be lower than would be expected, NRCS Hydrologist Karl Wetlaufer said.
“This is a very important time of the year when it comes to water resources because peak snowpack accumulation generally occurs in mid-April,” Wetlaufer said.
Cloud seeding may increase snowpack
Kanzer coordinates the Colorado River District’s cloud seeding program, which could increase snowfall from winter storms throughout Western Colorado and the West by up to 15%, Kanzer said.
For cloud seeding to work, clouds must contain super-cooled water between 5 and 23 degrees, cold enough to form ice crystals around tiny particles of silver iodide that are fired into the moisture-laden clouds, usually with propane-fired burners on the ground.
Silver iodide has been proven to be safe for the environment, Kanzer said.
The super-cooled liquid water freezes onto the silver iodide particles, building ice crystals that grow into snowflakes. More snowflakes mean more water, Kanzer said.
Technology can help find those snowflakes, Deems said. He runs a company called Airborne Snow Observatory that uses Light Detection and Ranging — LIDAR — to measure snow across the entire landscape. Pulses of scanning laser light are shot from a plane toward the earth and reflect off the snow. With that data, they build a three-dimensional picture of the snowscape, detailed enough to show deep pockets of snow below bare slopes where avalanches occurred, or even areas where snowmaking was used to make terrain parks on a ski run.
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