The linked reference discusses newly documented deep groundwater sources in California's Central Valley. If used wisely this could help with drought conditions; if used unwisely exploiting this resource could damage the environment, infrastructure and might constitute inter-generational theft associate with "Tyranny of the Contemporary":
Mary Kang and Robert B. Jackson (June 2016), "Salinity of deep groundwater in California: Water quantity, quality, and protection", PNAS, doi: 10.1073/pnas.1600400113
http://www.pnas.org/content/early/2016/06/21/1600400113Significance
Groundwater withdrawals are increasing across the United States, particularly in California, which faces a growing population and prolonged drought. Deep groundwater aquifers provide an alternative source of fresh and saline water that can be useable with desalination and/or treatment. In the Central Valley alone, fresh groundwater volumes can be increased almost threefold, and useable groundwater volumes can be increased fourfold if we extend depths to 3,000 m. However, some of these deep groundwater resources are vulnerable to contamination from oil/gas and other human activities. Our findings provide the first estimates, to our knowledge, of underground sources of drinking water depths and volumes in California and show the need to better characterize and protect deep groundwater aquifers.
Abstract
Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and gas extraction, and this activity has created both valuable data and risks to groundwater quality. Assessing groundwater quantity and quality requires baseline data and a monitoring framework for evaluating impacts. We analyze 938 chemical, geological, and depth data points from 360 oil/gas fields across eight counties in California and depth data from 34,392 oil and gas wells. By expanding previous groundwater volume estimates from depths of 305 m to 3,000 m in California’s Central Valley, an important agricultural region with growing groundwater demands, fresh [<3,000 ppm total dissolved solids (TDS)] groundwater volume is almost tripled to 2,700 km3, most of it found shallower than 1,000 m. The 3,000-m depth zone also provides 3,900 km3 of fresh and saline water, not previously estimated, that can be categorized as underground sources of drinking water (USDWs; <10,000 ppm TDS). Up to 19% and 35% of oil/gas activities have occurred directly in freshwater zones and USDWs, respectively, in the eight counties. Deeper activities, such as wastewater injection, may also pose a potential threat to groundwater, especially USDWs. Our findings indicate that California’s Central Valley alone has close to three times the volume of fresh groundwater and four times the volume of USDWs than previous estimates suggest. Therefore, efforts to monitor and protect deeper, saline groundwater resources are needed in California and beyond.
Also see:
http://www.climatecentral.org/news/water-windfall-drought-stricken-california-20481Extract: "California’s Central Valley has three times more freshwater in underground aquifers than previously thought, drinking water that could help the state weather future drought and fortify itself against a changing climate, according to a new Stanford University study.
But tapping that water, locked thousands of feet beneath the ground, will be expensive and comes with an enormous risk — it could cause the valley floor to sink, according to the study, published Monday in the Proceedings of the National Academy of Sciences. Sinking land in the Central Valley is threatening roads, homes and other infrastructure, and reduces the amount of water some aquifers can hold.
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“We're not advocating running out and drilling lots more groundwater wells,” Jackson said. “The Central Valley's been in denial about groundwater overdrafts for years. We need to consider ground subsidence. We also need to think about oil and gas activities directly in and around freshwater aquifers. Is that the best use of the resource long term?”
California’s water agency, the State Department of Water Resources, is concerned about the long-term implications of possibly using — and using up — a newly found reserve of freshwater.
“Understanding the total aquifer capacity is valuable from a technical standpoint, but a more useful estimate would be how much of the aquifer can we truly utilize before we experience significant impacts to surrounding agricultural, urban and domestic water users, to public infrastructures, to the environment and to the aquifers’ ability to recharge in a reasonable time frame,” said Lauren Hersh, spokeswoman for the California Department of Water Resources’ Sustainable Groundwater Management Program."