Drought

Colorado River Groundwater Disappearing at 'Shocking' Rate

As the Southwest's drought has worsened in the last decade, making surface water scarce, millions of people are drawing more heavily on underground water supplies. The water is coming out faster than it's being replenished, a new study finds.

Between December 2004 and November 2013, more than 75 percent of the water lost in the Colorado River Basin was from groundwater, according to the study. The region has been in a drought since 2000, according to the U.S. Drought Monitor.

The results show that groundwater is already being used to fill the gap between the demands of the region's millions of residents and farmers, and the available surface water supply, the researchers said.

The Colorado River Basin stretches across seven states: from Wyoming across Colorado, Utah, Arizona, New Mexico, Nevada and California. Its groundwater is stored in underground aquifers and is sucked from the ground by wells. If water is removed from an aquifer faster than it can be replaced, eventually the wells will go dry.