“Water Windfall” Discovered Under California’s Drought-Stricken Central Valley

Though the aquifer could help with the current and future droughts, researchers caution getting too greedy with the resource

Drought Locks
Andrew Hart /Flickr

California’s megadrought is stretching into its fifth year, and as the best hope for rain, El Niño, fizzles, the outlook is grim. While Northern California's winter precipitation approached normal, 60 percent of the state remains in a severe drought.

So a new discovery under the Central Valley has residents excited; researchers from Stanford mapped out a deep groundwater reservoir under the Valley that holds three times more water than previously thought. They recently published their results in the journal Proceedings of the National Academy of Sciences.

“It's not often that you find a ‘water windfall,’ but we just did," study co-author Robert Jackson says in a press release. “There's far more fresh water and usable water than we expected.”

Ria Misra at Gizmodo reports that the researchers estimate the reservoir holds 2,700 cubic kilometers of water or approximately 713 trillion liquid gallons. That’s more than Lake Erie and Lake Ontario combined.

The researchers analyzed data from more than 360 oil and gas fields in an eight-county area. Previous studies were based on estimates of water down to 1,000 feet below the surface. But the new study examines the water volume down to about 3,000 feet.

Despite the depth, Jackson tells Misra that the water is still retrievable. But the big question now is whether people should actually go after it. Pumping for groundwater can cause big changes to an area. Extracting during the drought has already led to subsidence in the Central Valley, which is sinking several inches per year, according to Dale Kasler, Ryan Sabalow and Phillip Reese at The Sacramento Bee. One area near Corcoran sank 13 inches in eight months. The sinking soil threatens the elaborate system of canals, pipes and bridges that transport water through the valley.

Besides impacting the geology of the surrounding area, Misra points out that the Central Valley Reservoir could be contaminated, since about 30 percent of the reservoir sits under oil and gas drilling sites. Even if the water is clean, Jackson cautions against exploiting the resource. “We need to be careful about using it,” Jackson tells Misra. “California’s groundwater pumping has been in overdraft for years, especially during the drought. Finding more water than expected doesn’t mean we should waste it.”

Hopefully, that won't be the case. After five years of drought, the conservation message finally seemed to get through. Between June of 2015 and April 2016, California reduced its water usage by 24.1 percent. But the optimism was short-lived. When the state recently allowed local water authorities to set their own water savings goals, nine out of 10 of the largest authorities set their target at zero percent.

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