Dust on Rockies Snow Quickens Melting, Disrupts Water Supplies
Dusty air blowing in from the drought-parched Southwest is subtly changing the color of the snow on the Rocky Mountains, affecting water supplies for millions of people in more than half a dozen states. The dust-darkened snow, tinged the color of cinnamon, absorbs more sun and melts earlier in the year—a problem for farmers and Western water managers, who can no longer count on thawing mountain snow packs to slowly deliver water downstream during the year at regular volumes. It also is bad news for Colorado's renowned ski resorts because dust gums up the slopes, making for a frustrating descent.
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A team of researchers detected five times as much dust in the Rockies in 2009 and 2010 as between 2005 and 2008, according to a study led by University of Colorado scientists released in November. A team of researchers detected five times as much dust in the Rockies in 2009 and 2010 as between 2005 and 2008, according to a study led by University of Colorado scientists released in November. The analysis, funded by the National Oceanic and Atmospheric Administration, estimated that the extra dust has caused the snow cover to disappear six weeks earlier than in the early 1800s, before settlers and their livestock started disturbing the soil in the Southwest, and reduced the Colorado River's annual runoff by 6%.
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The phenomenon is worsening the water woes in the Colorado River watershed, which supplies water to some 40 million people downstream in seven U.S. states and Mexico, and has been in a drought since 2000. Lake Mead and Lake Powell, its biggest reservoirs, are below 50% of their capacity.
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The federal Bureau of Reclamation, which helps manage the Colorado River, and officials from the states fed by it have looked into ways to stop the dust from blowing away in the first place. Options include replanting bare earth or spraying it with special bacteria to build up its crust.
Meanwhile, some water managers are talking about raising the walls of dams to capture bigger gushes of water, because the earlier snowmelts are resulting in torrents earlier in the year, when the water isn't yet needed by farmers, ranchers and other consumers. "We can't always capture all of the spring runoff," said Ryan Christianson, a Bureau of Reclamation water manager in western Colorado.
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