Despite winter rains and the lifting of urban conservation rules this month, California is still desperate for water. Reservoirs in Southern California are low, and we’re sucking groundwater from the Central Valley.
But what if there’s a vast pool of unidentified water? How much would we use immediately, how much would we save and how would we protect it?
Our new study published this week in the Proceedings of the Academy of Natural Sciences concludes that the Central Valley has almost three times more fresh water underground than the state estimates. Previous estimates are decades old and include only data for the top 1,000 feet or less. Most of the extra fresh water we identified is between 1,000 and 3,000 feet underground.
We also provide the first estimate for slightly saltier water that needs treatment before reaching our taps. Groundwater desalination is increasingly common here and elsewhere. A facility in Chula Vista is doubling its capacity. Other states, including Texas and Florida, and countries, including China and Australia, are also desalinating brackish ground water. It’s a resource we may need in the future.
Having more water than expected is good news, but our work raises some concerns. If pumping increases, so will land subsidence. Portions of the Central Valley have already dropped by tens of feet as shallower ground water disappeared. Subsidence permanently reduces the ground’s ability to hold water and can damage canals, buildings and other infrastructure.
Another concern is how common it is for oil and gas activities to occur directly into fresh and usable groundwater. We identified hundreds of cases where companies injected chemicals into fresh water through hydraulic fracturing and other processes. In Kern County, the core of California’s oil and gas industry, one in every six cases occurred directly into fresh water aquifers.
The 1974 federal Safe Drinking Water Act protects the quality of all water sources that are or could be used by people. The act requires companies to obtain permits whenever they use underground injection to dispose of chemicals.
The 2005 Energy Policy Act amended the Safe Drinking Water Act to clarify that the injection of fluids underground for hydraulic fracturing was not covered. To the industry, the act reaffirmed previous policy. To environmentalists, it exempted hydraulic fracturing from the act.
California’s recent Sustainable Groundwater Management Act and the Well Stimulation Bill both mandate new monitoring and data collection. That’s good news, but both of these efforts emphasize shallow aquifers only.
Assembly Bill 1755, scheduled to be heard Tuesday by the Senate Committee on Natural Resources and Water, establishes a shared water database for surface and groundwater and water diversions. Unfortunately the bill, authored by Assemblyman Bill Dodd, a Napa Democrat, doesn’t include data collection from the 2014 Well Stimulation Bill. California should be banking public water data everytime someone drills an energy or public water well.
The Legislature should consider whether additional safeguards are needed for energy extraction in groundwater. Extra permits may sometimes be warranted, with potential restrictions on oil and gas activities in freshwater aquifers above 3,000 feet. Such a change would affect only a minority of oil and gas operations.
There’s a windfall of water below our feet. Now that we know it’s there, California should start planning how best to use or save it.
Rob Jackson is a professor at Stanford University’s School of Earth, Energy & Environmental Sciences and can be contacted at firstname.lastname@example.org. Mary Kang is a postdoctoral researcher at the school and can be contacted at email@example.com.