California's groundwater shrinking because of agricultural use

New data from satellites show the vast underground pools feeding faucets and irrigation hoses across California are running low, a worrisome trend federal scientists largely attribute to aggressive agricultural pumping.

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.

Developers and cities dependent on the tight supplies also have joined the well-drilling frenzy as the crisis has deepened.

NASA scientists and researchers from UC Irvine presented their findings at a recent conference, showcasing data from twin satellites that pick up changes in the aquifers coursing underneath the state.

The NASA mission represents the first attempt to use space-based technology to measure how much groundwater has been lost in recent years in California and elsewhere in the world.

From October 2003 through March of this year, Mr. Famiglietti and his team tracked how Earth's gravitational pull on the satellites changed as the amount of water stored in the Sacramento and San Joaquin river basins dried up.

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