Deep aquifers could provide ‘water windfall’ to California

New research appearing in this week’s edition of journal Proceedings of the National Academy of Sciences presents both good and bad news for the drought-stricken residents of  Central Valley in California: unexpectedly high amounts of groundwater that will be difficult to access.

According to study co-authors Robert Jackson and Mary Kang from Stanford University, prior estimates of groundwater in the region were based on decades-old data that only extended to a maximum depth of 1,000 feet. As such, it failed to account for water contained in deep aquifers and accounted for as little as one-third of the groundwater actually in the Central Valley.

“It’s not often that you find a ‘water windfall,’ but we just did,” Jackson, the Michelle and Kevin Douglas Provostial Professor at the School of Earth, Energy and Environmental Sciences, said in a statement. “There’s far more fresh water and usable water than we expected.”

Unfortunately, actually using that water to provide relief to the area’s residents may be easier said than done, he and Kang reported, as it might be difficult to find an economically feasible way to use it, and it could be difficult to prevent it from becoming contaminated by petroleum-related activities. Nonetheless, the findings provide hope to drought victims everywhere.

Concerns over fracking, salinity of water could hamper usage

California has been experiencing a severe drought for the past five years, and in 2014, Governor Jerry Brown declared a state-wide drought emergency. To keep up with the demand for H2O, the state has become increasingly reliant upon groundwater sources, according to the authors.

In years past, water contained in aquifers 1,000 feet beneath the surface was “too expensive to use,” but these days, it is “used widely,” Jackson explained. As part of their research, he and his colleague reviewed data from 938 oil and gas pools and more than 35,000 oil and gas wells, and found that factoring in deeper sources of groundwater could increase the usable amount to 2,700 cubic kilometers, or nearly three times current estimates for the Central Valley.

The catch is that much of that water is between 1,000 and 3,000 feet underground, meaning that it will be more expensive to pump to the surface. Also, Jackson and Kang are concerned that accessing the water in these deeper aquifers may exacerbate the ground subsidence in the region, causing the gradual sinking of the land to worsen, and that the water in these aquifers could have higher levels of salt concentration, requiring extensive desalination treatments to make it usable.

The researchers are also concerned that petroleum-related drilling activities are taking place in up to 30 percent of the sites where these deep aquifers are located. While the fact that hydraulic fracturing is taking place in the vicinity of groundwater does not render that source unusable, it is a cause for concern, according to Kang.

“No one is monitoring deep aquifers. No one’s following them through time to see how and if the water quality is changing. We might need to use this water in a decade, so it’s definitely worth protecting,” the postdoctoral associate explained, adding that her team’s findings “are relevant to a lot of other places where there are water shortages, including Texas, China and Australia.”

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Image credit: Rob Jackson, Stanford University

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