The Science of Sustainability

Water Banks: A Hedge Against Shrinking Supplies in a Changing Climate

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When you make that long drive up or down I-5, look east. You see fields and orchards stretching to the Sierra, livestock and this time of year, lots of tomato trucks. What you don’t see is California’s largest permanent reservoir. Because it’s underground in the rock formations known as “aquifers.”

Central Valley growers often pump groundwater to cover shortfalls when surface water is scarce. Some farms are entirely dependent on groundwater. Photo: Craig Miller

For years, farms and cities have pumped water out to meet their needs. But now, as water supplies dwindle, there’s a major movement afoot to put some water back.

On a recent trip to Kern County, Harry Starkey unlocked the gate to some big electric pumps, to explain how. We were somewhere west of Bakersfield, surrounded by low-lying fields known as the “North Recharge and Recovery project for the West Kern Water District."

Starkey is general manager of the District. But he’s also a banker. And these pumps are his “ATM.” Deposits are made here–not in dollars–but in acre-feet of water.

“It’s a lot more impressive when there’s water in it,” said Starkey. On this predictably hot, dry day in the San Joaquin Valley, there was no water anywhere in sight.

West Kern was the first to formally start using the aquifers that lie underneath the San Joaquin Valley as the vault for what’s come to be known as “groundwater banking.” That was nearly 40 years ago. Now it’s one of almost a dozen groundwater banks in the region, designed to capture water in wet years and save it for a non-rainy day.

“We can take these high-flow occurrences, these flashy occasions when water arrives and there’s no home for it, the farmers don’t need it, the reservoirs are full in southern California, and then we have the ability to store that water underground,” explained Starkey.

His district doesn’t have any groundwater of its own. It’s had to buy land outside the district and pipe water to it, to let it soak in.

“And so what you’re looking for are sandy soils,” he continued. “And where do you find those? You find them proximate to river courses.”

Tapping the occasional spring pulse from the Kern River and other sources, water banks in this part of state have been able to squirrel away as much as three million acre-feet of water, equivalent to more than half the capacity of Shasta Lake…as near as they can tell.

It’s not exactly the kind of banking you’re used to, where you go down to the ATM, feed it some cash or a check, it spits out a receipt and you know exactly how much money you have in your account and how much you can take out. With groundwater banking, the “vault” is an unseen rock formation somewhere underground, so checking your balance involves a little more guesswork.

“Right now, it’s ‘current balance’ we think,” says Eric Averett, who runs the Rosedale-Rio Bravo Water Storage District on the west side of Bakersfield. “But everyone’s looking at that balance and saying, ‘I’m not sure I agree with that.’” In 2010, his district ended up in court with some neighboring water bankers, when it seemed like some of his customers’ “deposits” had diminished. Their wells were drying up.

Harry Starkey at the “ATM.” Pumps like this are the tools for making “deposits” and “withdrawals” at Kern County’s various water banks. Starkey’s West Kern Water District is adding a solar array to power these pumps. Photo: Craig Miller

“Clearly the groundwater system is a dynamic system,” he told me. “It’s like a river underneath the ground, and it does move and the benefits associated with the water when you put them into the ground are transient. And I think we’re learning that.”

They’ve learned, for instance, that about four percent of the water put into the ground may not come back out. It can migrate to another place and become irretrievable–think of it as Nature’s ATM fee.

Still, groundwater banking is getting big buzz in water circles of late, because frankly, it beats the alternative: building more dams and reservoirs to store surface water. It beats it from a financial standpoint–and is far more palatable to environmentalists.

Not that it’s cheap. It takes a lot of expensive plumbing to pump and move the water around to where it’s stored and retrieved. Districts down here just completed a $60 million-dollar expansion of something called the Cross Valley Canal, to shuttle water back and forth between the east and west sides of the Valley. But that’s chicken feed compared to the price of a new dam.

“I think water banking has proven out,” says Starkey. “It’s now sexy to kind of embrace it and look at it and people are wanting to borrow from what’s being done here.”

He says water planners and managers from all over the world have come through to study Kern’s approach to groundwater banking. It’s not surprising. Aquifers around the world are severely overdrawn, including some in the Central Valley—in particular, the area near Bakersfield known as the Tulare Basin. Managing Southern California’s surface and groundwater together, aan approach known to water wonks as “conjunctive management,” could ease that problem and mean far less reliance on water imported from the fragile Sacramento Delta–if they can get it right.

“Within Kern we’re saying we better start doing these things, and we better start doing them together,” concedes Averett. He and others have put their legal squabbles on hold while they work out the kinks. California’s groundwater has been called the least monitored, least regulated in the nation. State regulators are under pressure to fix that and are watching this experiment closely.

“There have been a few hiccups along the way,” says Ellen Hanak, a water analyst with the Public Policy Institute of California. But Hanak is impressed with the experiment so far, and agrees that in the long run, the most efficient way to manage groundwater is by the folks sitting on top of it.

Officials in the Valley are racing to prove that they can manage groundwater resources without more regulation. “We understand it from a technical standpoint, from an institutional standpoint, in a way that the state of California never could,” says Starkey. His colleague Averett puts it more bluntly: “We’re all kind of in this together, sink or swim. We all rely upon this geologic formation for our groundwater. And you know, we’re gonna live or die together.”

The television documentary, Heat and Harvest, premieres tonight at 7:30on KQED 9. And you'll find the entire multimedia series on KQED’s Heat and Harvest website.

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Category: Climate, Environment, Radio, Water

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About the Author ()

Craig is KQED's science editor, specializing in weather, climate, water & energy issues, with a little seismology thrown in just to shake things up. Prior to his current position, he launched and led the station's award-winning multimedia project, Climate Watch. Craig is also an accomplished writer/producer of television documentaries, with a focus on natural resource issues.