Aaron Fukuda admits that the 15-acre sunken field behind his office doesn't look like much.
It's basically a big, wide hole in the ground behind the headquarters of the Tulare Irrigation District, in the southern part of California's fertile Central Valley. But "for a water resources nerd like myself, it's a sexy, sexy piece of infrastructure," says Fukuda, the district's general manager.
This earthen basin could be the key to survival for an agricultural community that delivers huge quantities of vegetables, fruit and nuts to the rest of the country — but is running short of water. The basin just needs California's rivers to rise and flood it.
When rains come in the winter and swell the rivers, Fukuda and his colleagues open some gates and send water through irrigation canals to fill this basin and lots of others they've set up. That captured water will seep into the ground, eventually finding its way to a natural aquifer system hundreds of feet below.
Water underground has become a scarce and regulated asset in the state. Farmers have pumped so much water from aquifers in this part of California that they've become depleted, threatening water supplies for agriculture and communities that depend on wells for their household water. A 7-year-old law, just now taking effect, strictly limits the amount that farmers can pump from those aquifers, and those limits could put some farmers out of business.
Water-capturing basins like this one, however, offer farmers a way to survive. That's because the new law treats the underground aquifer like a bank account. If farmers deposit water into that account when water is plentiful, they can draw more water out when they need it, in years of drought. "It really is the difference between our community surviving and not," Fukuda says.
Floods are going from nuisance to lifeline
In the past, many Californians considered the winter floods a nuisance, Fukuda says. Now, that has now changed completely. "It's liquid gold," he says. "Cold, crisp floodwater is gold these days."
Farmers and water managers in the southern part of the Central Valley, where the water problem is most severe, are grasping at the water banking idea like a lifeline. Jon Reiter, a rancher and water consultant, works with some of them.
He shows me a field of grapes, destined to become raisins. The soil is sandy and looks as if it could absorb any water that landed here. There's an embankment around three sides of the field already. "You could imagine how much water you could store in the ground in a location like this," Reiter says.
The owner of this field, he says, "has made the determination that he would be willing to actually remove the raisins" and use the land instead to capture water. The water he would "sink" might be more valuable to him than his raisin crop because it could earn him the right to pump more water from the aquifer during a future drought to irrigate other fields.
Don Cameron, the owner of Terranova Ranch near Helm, Calif., has even bigger ambitions. Cameron's farm relies almost entirely on groundwater. He's been watching the underground water level fall for years and worrying about the future.
Ten years ago, during a winter with lots of rain, he decided to flood some vineyards and orchards, to see if he could replenish the aquifer without even clearing land for a dedicated "recharge basin." "A lot of people were skeptical, our neighbors especially," Cameron says. "I mean, they thought we were crazy. That we were going to kill our vineyard."
In fact, the grapevines and trees survived just fine, and the experiment boosted groundwater levels below his field. Further experiments, some carried out in collaboration with researchers at the University of California, Davis, confirmed the feasibility of this "on-farm recharge." Now Cameron is persuading his neighbors to do the same thing. Together, they could potentially flood tens of thousands of acres.
This is only possible, though, because Cameron happens to be in a fortunate location, right next to a branch of the Kings River, which in turn is connected to a big canal that's a major artery in California's vast water distribution system. That channel is bone-dry at the moment, but in years of heavy rains, it can fill with water. Many other farmers who are dependent on groundwater, and who will be hit hardest by the new law limiting its use, can't make "deposits" in their underground bank account because they have no access to floodwater. They're not connected to the network of ditches and canals that would be needed to carry floodwaters to their fields.
All that Cameron needs is for Mother Nature to deliver a flood. "I know we'll have another one," he says. "There is no doubt in my mind that we will flood again. We may even see more severe flooding in the future."
Climate experts agree that this is likely. In the past, California relied on precipitation arriving as snow in the Sierra Nevada mountains. The high-altitude snowpack acted as a giant reservoir, releasing water into rivers slowly as it melted. In the future, more of that water will arrive as rain, flooding quickly into rivers. The biggest reservoir available to store it may turn out to be underground, in the aquifer that California's farmers have drained for most of the past century.
Will this solution fall short?
This won't solve all of the Central Valley's water problems, though. For one thing, there still won't be enough water available to fully recharge the aquifers. Aggressively capturing and storing floodwaters could make up for 40% to 50% of the current groundwater deficit at best, according to Reiter.
In addition, recharging the aquifer could have mixed effects on the Central Valley's other big groundwater problem: contamination of wells with agricultural chemicals. These include nitrates from fertilizer and cattle waste. The problem is most severe for low-income communities that rely on shallow wells for household water use.
Flooding more land probably will flush those agricultural pollutants into aquifers, says Helen Dahlke, a hydrologist at the University of California, Davis. "We often see a spike in nitrate, for example, at the groundwater table below a recharge site," she says.
In the long run, though, she thinks it will be good for water quality. "Most of the water that we use for recharge is very clean, because it comes from rainfall or snowmelt from the Sierra Nevada Mountains," she says. "Eventually there will be a pulse of clean water also coming into the aquifer, which can dilute many of the pollutants that have moved into the groundwater over the last couple of decades."
She points to the experience of a small community in Tulare County called Okieville. There are parts of the community where wells show high levels of contamination. But along its southern edge, there's a groundwater recharge basin that the Tulare Irrigation District regularly fills with floodwater. People who live near that basin have enjoyed reliable supplies of clean water from their wells.
The irrigation district now is planning to build a new recharge basin on the other side of Okieville. "The idea is we can begin to shove water underneath their community. Good, clean water," says Aaron Fukuda, general manager of the irrigation district. "The water quality, we hope, gets better."
AILSA CHANG, HOST:
In the heart of California, an area that's plagued by drought, farmers and water managers cannot wait for a year with lots of rain. Of course, the water is good for crops, but they also want to capture the water to store in natural aquifers. For people who rely on them, it could mean survival. NPR's Dan Charles has the story.
DAN CHARLES, BYLINE: There's a big patch of dirt behind Aaron Fukuda's office at the Tulare Irrigation District in California's Central Valley that he gets very excited about.
AARON FUKUDA: For a water resources nerd like myself, it's a sexy, sexy piece of infrastructure (laughter).
CHARLES: It's a 15-acre sunken field just sitting here surrounded by pistachio orchards and cornfields. It was built to capture a flood. California does get floods sometimes during the winter. Fukuda says, in the past, a lot of people just considered those winter floods a nuisance. But among people here who grow a lot of the country's vegetables and fruit and nuts, that attitude has changed completely.
FUKUDA: It's liquid gold. Cold, crisp flood water is gold these days.
CHARLES: When it starts raining and the rivers rise, Fukuda and his colleagues open some gates and send water surging through irrigation canals into a bunch of giant basins like this one.
FUKUDA: We fill everything up. This will be brimful.
CHARLES: So when it's full, how deep is the water?
FUKUDA: I think it's about 6 or 7 feet deep.
CHARLES: And then the water seeps slowly into the ground - eventually, all the way to the aquifer hundreds of feet below us. This is called a groundwater recharge basin.
FUKUDA: It really is the difference between our communities surviving and not.
CHARLES: That water has become precious because it's now a scarce and regulated asset. Farmers have pumped so much water from their wells over the years, the aquifers have become depleted. A new law just now taking effect will limit that pumping, which will hurt some farmers. But the law also says if people replenish the aquifer, like making deposits in an underground bank account, they'll be allowed to pump more out later when the dry years come. And farmers all over the Central Valley are grasping this idea like a lifeline. Jon Reiter, a rancher and water consultant, works with some of them.
JON REITER: I want to show you over here.
CHARLES: This is your friend's vineyard?
REITER: Yes, this is raisins.
CHARLES: The soil's sandy, looks like it would just suck up water. There's already an embankment around three sides of this field. It's almost a ready made basin for flood water.
REITER: But you can imagine how much water you could get stored into the ground in a location like this.
CHARLES: But he's growing raisins.
REITER: He is, and he's made the determination that he would be willing to actually remove the raisins.
CHARLES: The water he'd store here might be more valuable to him than the raisins he'd grow because it would earn him the right to pump more water from the aquifer during a future drought to irrigate some of his other fields.
REITER: It's like a savings account.
CHARLES: And another farmer half an hour southwest of Fresno may have the biggest groundwater ambitions of all. His name is Don Cameron. He's been worried about the aquifer for many years. Ten years ago, during a winter with lots of rain, he decided to use his irrigation setup to just flood some of his vineyards and orchards at a time when they didn't need water.
DON CAMERON: A lot of people were skeptical - our neighbors, especially. I mean, they thought we were crazy, that we were going to kill our vineyard.
CHARLES: But the grape vines and trees survived just fine, and water levels in the aquifer increased. Now, Cameron's persuading his neighbors to do the same thing on their farms, creating, in effect, a recharge basin that could cover tens of thousands of acres. All he needs is for Mother Nature to deliver a flood.
CAMERON: I know we'll have another one. There is no doubt in my mind we will flood again. And we may see more severe flooding in the future.
CHARLES: Climate experts agree. Warmer temperatures will mean less snow, but more rain in the Sierra Nevada mountains, so it will runoff and flood more quickly. And the biggest reservoir available to store it all is underground, that aquifer that California's farmers have been draining for most of the past century. Dan Charles, NPR News. Transcript provided by NPR, Copyright NPR.