Streamflow of the Colorado River Basin is the most over-allocated in the world. Recent assessment indicates that demand for this renewable resource will soon outstrip supply, suggesting that limited groundwater reserves will play an increasingly important role in meeting future water needs.
Scientists at the University of California, Irvine, and NASA analyzed data (2003-2013) from a satellite that measures underground water reserves to calculate that the Colorado River Basin has lost 65 cubic kilometers—that’s 17.3 trillion gallons—of water between December 2004 and November 2013. That represents twice the capacity of the United States’ largest reservoir, Lake Mead in Nevada. Most worrying, 75 percent of the loss came from groundwater supplies.
“We don’t know exactly how much groundwater we have left, so we don’t know when we’re going to run out,” Stephanie Castle, the report’s lead author and a water resources specialist at UC Irvine, said in a statement. “This is a lot of water to lose. We thought that the picture could be pretty bad, but this was shocking.”