Stanford University released a study this week stating that California has three times more useable groundwater located in deep aquifers than previously estimated.  This might come as welcome news to a state that continues to suffer through a historic drought.  The researchers found that fresh groundwater was available at depths previously thought to be too deep to contain fresh water.

At the outset, readers should note that “freshwater” and “drinking water” are terms of art having regulatory and legal distinctions, and ultimately making a difference for the public welfare. The definition of freshwater varies depending on the state or federal agency; however, freshwater is generally defined as having less than 3,000 mg/L of total dissolved solids (“TDS”).  Underground Sources of Drinking Water (“USDW” or “drinking water”) as defined by the Environmental Protection Agency include groundwater aquifers with less than 10,000 mg/L TDS.  For reference, seawater contains approximately 35,000 mg/L TDS.

Historically, California’s fresh groundwater supply was thought to be limited to water found above 1,000 feet. However, the researchers determined that the mean base of fresh water (“BFW”) in five Central Valley counties (Kern, Fresno, Solano, Colusa, and Yolo) ranged from 1,345 feet (Colusa) to 2,204 feet (Kern).  The base of drinking water is considerably deeper than the freshwater.  Specifically, USDW can be found in Kern and Los Angeles Counties at depths deeper than 8,200 feet.

Overall, most of the groundwater volume originates from the more accessible layers above 3,000 feet, but deeper formations (between 3,000 and 10,000 feet) still represent 26% and 42% of the freshwater and USDWs, respectively, in the top 10,000 feet.

The study suggests that desalinating this underground water would be cheaper than desalinating seawater, as the new desalination plant in the San Diego area has begun to do since coming online on December 14, 2015. The Carlsbad desalination plant in San Diego is desalinating approximately 37 billion gallons of seawater annually at a cost of over $2,100/acre ft, while expanding the region’s water supply portfolio.

The implications of these newly discovered underground treasure-trove of water are yet to be seen, though some reactions from academics and others in the industry indicate the purported “windfall” is already known and bears its own risks with energy costs of extraction at such great depths and potentially undesirable impacts like subsidence given interconnectivity of deep and shallow aquifers. Also, environmental activists likely will renew their call for greater restrictions on oil and gas development and hydraulic fracturing, despite the fact that, generally, oil and gas activities occur at depths deeper than the base of freshwater or drinking water and adverse health impacts have not been shown to occur.

The Division of Oil, Gas and Geothermal Resources has repeatedly stated that there has been “no contamination of water used for drinking or agricultural purposes related to underground injection by the oil and gas industry” and “no evidence has been found that underground injection has damaged sources of potential drinking water.”  Additionally, U.S. Environmental Protection Agency, found that hydraulic fracturing posed no “widespread, systemic” threat to drinking water.

Additionally, it will be interesting to see how this study affects the creation of Groundwater Sustainability Plans (“GSPs”) under California’s Sustainable Groundwater Management Act (“SGMA”). These GSPs have the potential to have far-reaching implications on the use and management of groundwater.

Ultimately, California groundwater and those reliant on this natural resource have much to focus on in the coming years as evolving regulations and management take form.