Study: Snowpack in greater decline in the Rockies
June 12, 2011
COLORADO SPRINGS – A new federal study suggests the snowpack declines in the Rocky Mountains in the last 30 years are greater than in the past few centuries.
That could strain cities whose water supplies are tied to mountain snowpack. Runoff from snow that accumulates at high altitude accounts for 60 to 80 percent of the annual water supply for more than 70 million people in the West, the U.S. Geological Survey says.
Historically, the northern Rockies have had large snowpacks when the southern Rockies had meager ones and vice versa, USGS said. But since the 1980s, there have been drops in snowpack along the entire Rockies and unusually severe declines in the north, its study found.
As of Friday, the Colorado snowpack was 248 percent of average, but the deep snowpack in the northern Rockies this year is “only a small blip” in a century-long snowpack decline, the agency said this week.
Previous studies by the USGS and others have said unusual springtime warming, more precipitation falling as rain instead of snow and earlier snowmelt have contributed to snowpack declines.
“What we have seen in the last few decades may signal a fundamental shift from precipitation to temperature as the dominant influence on western snowpack,” the study’s lead author Gregory Pederson said in a written statement.
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Colorado Springs Utilities gets all its water from snowpack from the Colorado, Arkansas and South Platte river basins. Colorado Springs Utilities water supply planning supervisor Abby Ortega told The Gazette that the utility’s records go back 100 years, and officials there have not noticed an overall trend of less snow and earlier melt-offs.
“There are definitely dry years and wet years, earlier runoff and later runoff, but it’s Colorado and the climate is widely variable,” Ortega said.
However she said other studies have warned of climate change and effects on snowpack.