California’s drought-stricken Central Valley has three times more groundwater than previously estimated, according to a new study by Stanford University scientists.

The research, published Monday in the journal Proceedings of the National Academy of Sciences, identified aquifers 1,000 feet to 3,000 feet deep holding hundreds of cubic miles of water.

Professor Robert Jackson and associate Mary Kang used data from 938 oil and gas pools and more than 35,000 oil and gas wells to measure both shallow and deep groundwater sources in eight California counties.

“It’s not often that you find a ‘water windfall,’ but we just did,” said Jackson. “There’s far more fresh water and usable water than we expected.”

“Our findings are relevant to a lot of other places where there are water shortages, including Texas, China and Australia,” said Kang, a postdoctoral associate.

Previous estimates of groundwater in California were based on decades-old data and only extend to a maximum depth of 1,000 feet. Until now, little was known about the amount and quality of water in deeper aquifers.

There are some drawbacks to using this new-found water, however. Jackson said the deeper water will be more expensive to pump, must be treated to remove salt, and could be contaminated by nearby oil and gas wells.

In addition, tapping these deeper aquifers might also exacerbate the ground subsidence – the gradual sinking of the land – that is already happening throughout the Central Valley.

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Chris Jennewein

Chris Jennewein is Editor & Publisher of Times of San Diego.