Researchers Find More Water Deep Under California| Fluence
Central Valley aquifers

Stanford researchers have found unexpectedly large groundwater resources under California’s drought-stricken Central Valley, home to large-scale agriculture, as well as oil and gas fields.

California is sitting atop more water than scientists originally estimated according to new research released by Stanford University researchers.

This water is stored deep underground in aquifers some 1,000 to 10,000 feet below the state’s Central Valley. This amount of usable fresh groundwater is almost triple the existing estimates, or 2,700 billion tons, at depths of less than 10,000 feet.

The news provides some hope for California, which is in the fifth year of severe drought. California Gov. Jerry Brown declared a drought emergency in 2014. The state has been increasingly turning to groundwater supplies to meet its ongoing water needs.

Before this study, estimates of available groundwater were based on decades-old data, most of which looked at water stores 1,000 feet or less under the earth’s surface. There was little information about the amount and quality of water in deeper aquifers.

Data From Oil and Gas Fields

To make their assessment, the Stanford researchers used data from 360 oil and gas fields, which include 34,392 wells across eight counties in the Central Valley, as well as in other locations in the state. Based on the data, they estimated the amount of water under entire Central Valley would be more than 3 billion acre-feet (3,900 km3) of both fresh and saline water.

Rob Jackson, who conducted the research with Mary Kang, the study’s lead author, told The Washington Post

There’s a lot more fresh groundwater in California than people know. […] It’s like a savings account. We can spend it today, or save it for when we really need it […] There’s definitely enough extra groundwater to make a difference for the drought and farmers

Other scientists specializing in groundwater research expect this finding will do little to change the state’s water crisis. It may actual spark controversy among those attempting to determine how water resources should be managed to benefit all the state’s residents and businesses.

Likely Complications

The findings are raising some questions, particularly, “What’s next?”

Most of the water is between 1,000 and 3,000 feet underground. This means more expenses associated with pumping it. More studies are needed to determine the effects on the land. Much of the Central Valley is already sinking from overdrawing shallow groundwater aquifers.

Graham Fogg, a hydrogeologist with the University of California-Davis, told The Washington Post:

Just because they’ve seen that the depth of freshwater in this basin is deeper than people thought, does not mean that you can go pump more freshwater out of this system at all. It unequivocally does not mean that.

Additionally, this groundwater is saltier, and could require treatment through brackish water desalination and other means.

Monitoring Quality of Groundwater

The researchers also are concerned about oil and gas exploration, which is occurring in roughly 30 percent of the sites where these deep groundwater resources are located. But, Kang says hydraulic fracturing or other activity near an aquifer doesn’t necessarily render the water unusable. Kang told the Stanford News Service these deeper aquifers need to be properly and regularly monitored to determine whether and how their water quality may be changing. This is especially critical if the state needs to start withdrawing water from these deep pockets in the future.

Researchers say the results point to the importance of better characterizing and protecting deep groundwater aquifers, especially in water-stressed areas.

Jackson said the next step is determining how best to manage this deep groundwater resource. He told The Washington Post:

I hope it prompts a conversation about monitoring and safeguarding our groundwater. […] We’re lucky that we have more than we expected. Now we need to use it wisely and take care of it.

The paper — “Salinity of deep groundwater in California: Water quantity, quality, and protection” — was published in the journal Proceedings of the National Academy of Sciences.

Image by Miguel Vaca, used under a Creative Commons license.