"The measurements show the amount of water lost in the two main Central Valley river basins within the past six years could almost fill the nation's largest reservoir, Lake Mead in Nevada.
"All that water has been sucked from these river basins. It's gone. It's left the building," says Jay Famiglietti, an earth science professor at the University of California, Irvine, who led the research collaboration. "The data is telling us that this rate of pumping is not sustainable."
Hundreds of farmers have been drilling wells to irrigate their crops, as three years of drought and environmental restrictions on water supplies have withered crops, jobs and profits throughout the San Joaquin Valley, where roughly half of the nation's fruits, nuts, and vegetables are grown."
NASA researchers say that more than three-quarters of the groundwater loss is due to agricultural irrigation.