Colorado River Basin groundwater, which takes a long time to recharge, is drying up at a rapid rate

The Colorado River Basin — which feeds water to 40 million people in parts of Wyoming, Colorado, Utah, New Mexico, Nevada, Arizona and California — is drying up faster than previously thought, according to a study by researchers at the University of California Irvine.

Bureau of Reclamation map: Colorado Basin and the areas it supplies

"In the past nine years, the basin has lost about 65 cubic kilometers of fresh water, nearly double the volume of the country’s largest reservoir, Lake Mead," Reid Wilson reports for The Washington Post. "About two-thirds of the water lost over the past nine years came from underground water supplies, rather than surface water." States are responsible for regulating groundwater, but some states like California have no groundwater management rules.

The main problem is drought, which has dropped Lake Mead to its lowest level since it was created in the 1930s, Wilson writes. "More than three quarters of the water lost over the past decade came from underground," which has researchers concerned. Stephanie Castle, lead author of the study, told Wilson, “You get a wet year, you get some precipitation, and those reservoirs can fill right back up. It can take years, or hundreds of years, to refill groundwater basins.” Researchers say climate change and stress brought on by growing populations in cities will only make the situation worse in coming decades. (Read more)