According to recent NASA satellite studies the western United States has been using up its underground water supply over the last 10 years in light of the drought.
According to the studies 75 percent of all the water from the Colorado River Basin has been lost through underground sources between 2004 and 2013. That amounts to 41 million acre of feet of freshwater. The Weather Chanel reports that 40 million people in seven southwestern states rely on the Colorado River as their primary source of drinking water.
"We don't know exactly how much groundwater we have left, so we don't know when we're going to run out," lead author of the study and University of California -Irvine water specialists Stephanie Castle. "This is a lot of water to lose. We thought that the picture could be pretty bad, but this was shocking."
The data from the study was collected from NASA's Gravity Recovery and Climate Experiment (GRACE) satellite. The satellite measures changes in ground water above and below the surface.
"There's only one way to put together a very large-area study like this, and that is with satellites," said Jay Famiglietti, senior water cycle scientist at Jet Propulsion Laboratory who is currently at University of California - Irvine.
Gizmodo reports that the GRACE satellite is like a large weighing scale in the sky. The amount of water in an area changes the overall mass of the area, which affects its gravitational attraction. GRACE measures the areas gravity and can show if an area is gaining or losing its mass in ground water.
The lose in ground water reveals that states are pumping more water from the Colorado River Basin in order to compensate for the lack of rain. And surface water.
The Los Angeles Times reports that the loss of ground water reflects long terms trends in ground water overdraft due to the increased reliance on wells after the drought settled on the region.
NASA notes that while surface water use is largely regulated and monitored the U.S. Bureau of Reclamation , the water that is pumped from underground is largely unregulated. Famiglietti feels that those who rely on the basin will definitely feel the effects if the pumping of ground water isn't regulated and that it also affects the surface water.
"Combined with declining snowpack and population growth, this will likely threaten the long-term ability of the basin to meet its water allocation commitments to the seven basin states and to Mexico," Famiglietti said.
