by Katie Valentine
Climate change and population growth will have serious effects on the water supply in the Colorado River Basin over the next 50 years, according to a newly-released federal study.
The study, which was funded by the U.S. Department of the Interior’s Bureau of Reclamation and the seven Colorado River Basin states, says that by 2060, the gap between river supply and water demand in the region will be 3.2 million acre feet. That’s more than five times the amount of water consumed annually by Los Angeles alone, and means that water management policies will need to be rethought in the Colorado River Basin states. Secretary of State Ken Salazar said the study should serve as a “call to action” to state and federal governments to create a plan for the future of the Colorado River.
“As a result of the projected population growth in the Southwestern states, and all of the states on the Colorado River Basis, and the reality of a changing climate, we’re going to be putting ever increasing demands on the Colorado River Basin,” Salazar said at a Colorado River Water Users Association conference in Las Vegas.
The study considered different scenarios of population growth and climate effects to come up with its projection. Under a warming climate scenario, it predicts a flow reduction in the Colorado River of about 9 percent, along with other climactic effects:
“Droughts lasting 5 or more years are projected to occur 50 percent of the time over the next 50 years. Projected changes in climate and hydrologic processes include continued warming across the Basin, a trend towards drying (although precipitation patterns continue to be spatially and temporally complex) increased evapotranspiration and decreased snowpack as a higher percentage of precipitation falls as rain rather than snow and warmer temperatures cause earlier melt.”
Already, the Colorado River Basin area has had to grapple with the effects of drought and increased temperatures. This spring, Colorado saw its worst drought since 2002, which contributed to devastating wildfires in the state. The state’s soil moisture over the summer was as low as 5 to 10 percent, which is well below the average moisture level of 40 percent. Last year’s warm winter caused record low snowpack levels in the region, which contributed to decreased river flow this year. And drought conditions don’t appear to be easing any time soon: NOAA’s seasonal outlook map for mid-November to late February predicted continued drought for the Colorado River Basin.
There are several options outlined in the study that would allow the River Basin area to cope with the projected water shortage, including water importation, desalinization of brackish or ocean water, expanding the reuse of municipal wastewater and changes to watershed management. One option – agricultural water conservation – is especially important, given that the 5.5 million acres of farmland supplied by the Colorado River is responsible for the majority of the river’s water demand. But municipal use is the fastest-growing sector, and so options for household and business water use reductions will have to be considered if water demand in the Colorado River Basin is to decrease.
Recently, Las Vegas, a city known for its over-the-top water displays, has put strict water restrictions in place to reduce residents’ household consumption. The city pays homeowners $1.50 per square foot to pull the grass out of their yard so that they won’t need to water it and fines residents if they don’t adhere to outdoor water use laws. Because of these efforts, Las Vegas has seen a decrease in household water use of about 30 percent over the past decade. As climate change impacts water supplies everywhere, more initiatives like this will have to be put in place, not only in desert cities like Las Vegas or places in the Colorado River Basin, but across the U.S.
Katie Valentine graduated from the University of Georgia with a degree in Journalism. She is an intern with the international climate team at the Center for American Progress.