Each year 35 billion cubic feet (261 billion gallons) of water are lost in the Colorado River watershed due to dust settling on snows near the headwaters. The amount lost is five times more water than needed to restore flows through the dried-out Colorado River Delta and is twice Las Vegas’ draw.
By Jonathan Waterman, National Geographic Grantee
At first glance, the September 20 report on the “Response of Colorado River runoff to dust radiative forcing in snow,” from the online version of the journal Proceedings of the National Academy of Sciences, wouldn’t seem to merit such wide play. But the study’s unabashed quantification of the startling loss of water due to dust coating the mountains that feed the Colorado River, allowed both mainstream and scientific journals to weigh in from coast to coast.
Each year, the study concludes, 35 billion cubic feet (261 billion gallons) of water are lost in this dust up. Annually, this is five times more water than needed to restore flows through the dried-out Colorado River Delta so that the river can once again reach the sea; twice Las Vegas’ draw; and enough to supply several dozen cities and thousands of farms that divert the Colorado River headwaters out of the river basin, under the Rockies through 12 tunnels, and onto the semi-arid plains of eastern Colorado.
Although the Colorado River is hardly the longest river, at 1,450 miles it is one of the steepest rivers. It drains 243,000 square miles (or a tenth of the continental U.S.’s land area), grows more than 3 million acres of farms, and slakes the thirst of nearly 30 million people. While the river’s demise has been foretold through all but the most entitled water owners, called buffalos, of the basin, the dust study is unique because it shows exactly how much water is lost to a seemingly arcane environmental factor that may be more related to population growth than climate change.
For those living outside the Rockies, in regions of more than 20 inches of annual rainfall, it’s tough sledding to visualize how dust on the mountains can diminish (according to the study) five percent of the river. But for residents in the semi-arid mountains or arid deserts of the west, these increasingly common dust storms plaster reddish-brown war paint on living-room picture windows, car windshields, or the snow-covered Rockies. For backcountry skiers, the spring snowfield dust is akin to skiing on glue.
“Dust can have an impact even when it’s too sparse to notice,” said study leader Thomas Painter, a snow hydrologist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “But it can get to the point where it looks like cinnamon toast.”
Normally a clean, white snow surface reflects 80 percent of heat back into the atmosphere. Dust, however, allows the snowpack to absorb more heat, and increases evaporation, which reduces the overall amount of water flowing from melting snowpacks, the Colorado River primary source. The dust speeds up snowmelt runoff by an estimated three weeks and wreaks havoc on the irrigation cycles of farms downstream. In addition, while the dust effectively creates an artificial and unnaturally early spring, it also accelerates the growth of plants that absorb more water. This plant growth accounts for the biggest water loss.
Photograph of Strontia Dam delivering Colorado River water to Denver by Jonathan Waterman, from his and Peter McBride’s forthcoming photography book, the Colorado River, Flowing Through Conflict.
The study notes that heavy dusting of the snow pack began with the settlement of the West in mid 19th century. By coring lake sediments in the Rockies, scientists have discovered that the current time period corresponds to a 500 to 600 percent increase in dust deposits. Throughout the dry southwest, domestic livestock, road building, and urban growth have repeatedly broken the fragile desert crusts that would otherwise prevent wind from carrying off desert soils. Continuing development throughout the burgeoning states of New Mexico, Arizona, and Utah allow the prevailing winds to carry off the dust and deposit it on the Colorado River’s lifeline: the snow-covered Rocky Mountains.
“Actions to stabilize soils and minimize activities that disturb soils could potentially decrease dust emissions and the loss of runoff,” Painter said. “Clean your snow, it lasts longer–it is that simple.”
As scientists, Painter and his coauthors have shone defining light onto the river crisis, along with a new path toward water sustainability, but the hard part comes in inspiring the lawmakers and water operators of the Colorado River Basin to implement these and other necessary actions to affect change.
Photograph by Peter McBride.
This is the fourth post in a series of Colorado River notes from Jonathan Waterman, author of two books about the Colorado River crisis: Running Dry: A Journey From Source to Sea Down the Colorado River; and the Colorado River: Flowing through Conflict. For more information on his Colorado River Project, visit his website and Save the Colorado’s website.
Photograph by Peter McBride.
Read more about the Colorado Delta on Alexandra Cousteau’s Blue Planet Expedition website. Waterman recently accompanied Cousteau down stretches of the Colorado River.
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