Dust on snow means less water in river
Both an article and an editorial have recently appeared in the Salt Lake Tribune regarding the overallocated water of the Colorado River. Conservation of water was mentioned but the relationship between how the land is managed in Utah and total water quantity in the Colorado River has been ignored.
The Colorado River is not isolated from the mountains and lands around it. Winter snowfall and the gradual melting of that snow in spring is the source of the water flowing in the Colorado River system upon which 27 million people in the desert southwest depend.
In Utah, desert soils are held in place by both physical and biological crusts that prevent the single inch of top soil from blowing away. Sometimes, it takes 50-250 years for these crusts to form, but when they do, they are very effective in preventing erosion and dust storms, even in high winds.
Unfortunately, when this crust is broken by tires, excessive livestock grazing, energy exploration and development, or even footsteps, our soil blows away in storms and can travel miles to coat the snow fields of the Rocky Mountains with Utah dust.
Snow coated with dust absorbs more heat from the sun than white snow and consequently melts faster with peak melt about a month sooner than clean snow. Earlier snowmelt means plants can be active for a longer time and more water will convert to water vapor and move into the atmosphere by evapotranspiration rather than remain as liquid water that flows into the river.
How does this affect water availability in the Colorado River? When the peak snowmelt occurs earlier, more than 250 billion gallons of water is lost. This is enough to supply Los Angeles for a year and a half; it is half of what Arizona takes down through its Central Arizona Project and twice what the city of Denver uses annually for its water supply.
This is a huge amount of water lost to the Colorado River and all those that depend upon it for life in the desert!
It doesn't have to be this way. We don't have to lose this precious water to dust! Better land management can recover and prevent this water loss.
The best way to reduce windborne dust from soil erosion is to prevent land use that disturbs the soil surface. When we stop soil disturbance and activities that damage the soil crusts, soil surfaces stabilize.
Permanent protection for Greater Canyonlands through national monument designation would not only preserve the beautiful canyons and unique wildlife, it would be a step toward mitigating the deposition of dust-on-snow that has reduced flows in the Colorado River.
It is a means of mitigating the water sources for millions of Americans and communities throughout the Southwest.
Marion Klaus is chair of the Utah Chapter of the Sierra Club. She lives in Park City.
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