How Stanford researchers discovered a gigantic underground reservoir in California's Central Valley

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LOS ANGELES, CA - FEBRUARY 4: A sign from wetter times warns people not to dive from a bridge over the Kern River, which has been dried up by water diversion projects and little rain, on February 4, 2014 in Bakersfield, California. Now in its third straight year of unprecedented drought, California is experiencing its driest year on record, dating back 119 years. Grasslands that support cattle have dried up, forcing ranchers to feed them expensive supplemental hay to keep them from starving or to sell at least some of their herds, and farmers are struggling with diminishing crop water and what to plant or whether to tear out permanent crops which use water year-round such, as almond trees. About 17 rural communities could run out of drinking water within several weeks and politicians are are pushing to undo laws that protect several endangered species. (Photo by David McNew/Getty Images) — A sign in Bakersfield warns people not to dive from a bridge over the Kern River, which has been dried up by water diversion projects and little rain.

Stanford scientists have found a large reservoir of water deep below the Central Valley — to the tune of 713 trillion gallons of water.

The Central Valley has been hit hard by the long-running drought. La Niña has failed to deliver the relief everyone was hoping for, but researchers at Stanford have discovered what could be good news for the region and for the state.

Stanford scientists have found a large reservoir of water deep below the Central Valley — to the tune of 713 trillion gallons of water.

There’s a catch, though: the water’s estimated to be anywhere between 1,000 to 3,000 feet underground, which means that extracting that water could hasten the sinking of the ground – something that's already happening in the Central Valley. Plus, scientists are worried that water that deep could be contaminated from oil and gas drilling in the region.

“We don’t want to fool the public into thinking that we suddenly have increased our water supply by a factor of 10,” said hydrologist Jay Famiglietti, a professor at UC Irvine and a senior water scientist at JPL.

While Famiglietti called deep brackish groundwater basins like the Central Valley reservoir “a resource,” he said that there are many uncertainties about the usage and usefulness of them.

“It’s not clear at what rate we should extract them, and when we will be able to do that without significant consequences," he said.

Stanford professor and co-author of the study Robert B. Jackson also urged the public to be cautious when interpreting his findings, especially regarding the apparently massive quantity of water in the basin.

“There are places where there is good fresh water available, but we’re not saying to run out and drill. We’re saying, let’s quantify this resource, let’s understand it, and ideally let’s save it for the future as a rainy day fund.”

Salinity of deep groundwater in California: Water quantity, quality, and protection

Guests:

Robert B. Jackson, co-author of study, “Salinity of deep groundwater in California: Water quantity, quality, and protection,” published Monday in the Proceedings of the National Academy of Sciences. He is a professor at the school of Earth, Energy & Environmental Sciences at Stanford University

Jay Famiglietti, a hydrologist and professor at UC Irvine. He is also a senior water scientist at JPL

This story has been updated.