The West is drying up.

Nature shares satellite data that shows not only lakes, rivers and reservoirs shrinking across the whole U.S. Southwest, but even water underground is going away:

To track groundwater losses, researchers used data from the Gravity Recovery and Climate Experiment (GRACE), a pair of satellites operated by NASA and the German Aerospace Centre (DLR) that measure variations in the gravitational pull of Earth. The team found that from December 2004 to November 2013, the Colorado River basin — which supplies roughly 40 million people in seven US states — lost roughly 65 trillion litres of fresh water. To determine how much of that was groundwater, they subtracted out water lost from surface reservoirs and soil.

The result was more than 50 trillion litres, roughly 1.5 more than the maximum capacity of the United States’ largest reservoir, Lake Mead in Nevada and Arizona. “It was way more than we ever thought,” says study co-author Jay Famiglietti, a water-cycle scientist at NASA’s Jet Propulsion Lab in Pasadena, California.

The problem is magnified by the fact that the groundwater is being removed from the ground faster than nature can replenish it. And as it dwindles, the cost to pump rises because the water has to come from greater depths. “At some point, it becomes more costly than it’s worth,” says [Jay Lund, a water-resource engineer and director of the Center for Watershed Sciences at the University of California, Davis].