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Researchers Say There’s Actually Plenty of Water Underneath California

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The problem is bringing it to the surface

El Niño is officially over, and with drought conditions in Southern California still looking pretty bleak, residents can’t be blamed for wondering if and when the state will simply run out of water. Fortunately, researchers from Stanford University say they have found a "water windfall" buried deep below the ground in the Central Valley. A study Monday published in Proceedings of the National Academy of Sciences finds the amount of usable groundwater in the area is almost three times more than previous estimates suggested.

According to the researchers, the Central Valley has stores of groundwater totaling 2,700 cubic kilometers. To put that number in perspective: All the reservoirs in the California State Water Project have a combined storage capacity of 7.2 cubic kilometers.

Obviously, the discovery of such a huge amount of water is exciting in the midst of a historic drought. Unfortunately, accessing it could prove to be tricky.

One of the reasons all that groundwater went undetected for so long is that much of it lies far beneath the surface. Previous estimates only probed about 305 meters below ground, while the authors of the study went looking for groundwater at depths of up to 3,000 meters. Most of the water they discovered is less than 1,000 meters deep, but bringing it to the surface could still be challenging.

For one thing, pumping groundwater in drought-afflicted areas can actually cause the land above to sink in a process called subsidence. Parts of the San Joaquin Valley are in fact sinking about an inch per year, with one two square-mile area subsiding close to a full foot annually. That kind of subsidence can cause tremendous damage to area infrastructure and increase the risk of flooding (assuming it ever rains in California again).

Deeper groundwater is also not likely to be potable right away, and would need to be treated at desalinization plants before it could be added to the local water supply. The good news on that front is that the groundwater is significantly less salty than ocean water, so the process of treating it would be much cheaper.

The study's authors also note that oil companies are actively drilling at nearly one-third of the sites where the groundwater is located. This leaves much of the water vulnerable to contamination.

Authors Mary Kang and Robert Jackson are calling for closer monitoring of water quality in these deep aquifers. "No one’s following them through time to see how and if the water quality is changing," Kang said. "We might need to use this water in a decade, so it’s definitely worth protecting."