Most of California has been struck by extreme weather conditions such as heat waves and droughts, particularly its Central Valley.

Unfortunately, the state is currently in its fifth year of severe drought, and Governor Jerry Brown declared a state of emergency in 2014.

But there might be hope. New research by Stanford University has revealed that the drought-stricken Central Valley actually contains three times more water underneath than what scientists had initially estimated.

Robert Jackson, co-author of the study, says it's not every day that scientists find a "water windfall," but they did. He says there are far more usable and fresh water beneath the valley than what they expected.

However, Jackson and his colleagues also warn that the real challenge is finding an economically feasible way to access this groundwater and protecting it from contamination from gas and oil activities.

California Groundwater

Previous calculations of groundwater in the state are based on decades-old research and only reach to a maximum depth of 1,000 feet (305 meters). Until now, there was little information about the quality and amount of water in deeper aquifers.

Jackson says water located a thousand feet below used to be too expensive to use, but today, because it is used widely, the good quality of water must be protected. And in order to meet the population's surface water needs, California is turning to its groundwater reserves.

Challenges To Face

In the new report, Jackson and his colleagues examined data from 938 oil and gas pools as well as more than 35,000 oil and gas wells to identify sources of shallow and deep groundwater in eight counties in California.

Stanford scientists said that when deeper groundwater sources are taken into account, the amount of accessible groundwater in the valley is actually equal to 2,700 cubic kilometers — almost thrice the state's current estimations.

However, although this may seem like a good news for California, scientists say the findings raise some concerns.

First, much of the water is located 1,000 to 3,000 feet (305 meters to 914 meters) underneath, so pumping it will be more expensive.

Second, without further investigations, tapping these deeper aquifers might aggravate the ground subsidence or the gradual sinking of the land, which is already occurring in much of the Central Valley.

Third, some of the deeper underground water contains higher concentrations of salt than shallower water, so treatments such as desalination are required before the water can be used for drinking or in agriculture.

Lastly, Jackson and his team are worried that because oil and gas drilling transpires directly into as much as 30 percent of the deep groundwater sites, there might be risks of contamination.

For instance, they found that in Kern County, one in every six oil and gas activities occurred directly into freshwater aquifers.

Mary Kang, Jackson's co-author, says what they are saying is that no one has been monitoring deep aquifers, and no one has been following through or checking whether water quality is changing.

"We might need to use this water in a decade, so it's definitely worth protecting," says Kang.

Details of the study are issued in the journal PNAS.

Watch the video below.