California wants to store floodwaters underground. It is more difficult than it looks

For much of the past few decades, when the skies did not produce enough water for his cows and crops, Dino Giacomazzi, like most farmers in the Central Valley of southern California, drew it from the ground. Underground aquifers were drained, vast bank accounts of stored water.

Now, after a historically wet winter, Giacomazzi and the state of California want to reclaim some of that water.

“It’s an obvious, win-win, multi-win opportunity,” said Giacomazzi, standing on his Central Valley farm, which relies on groundwater to grow almonds, lettuce and tomatoes for pizza sauce.

More water stored underground means fewer flooded farms and more water available to farmers like him during the next inevitable drought.

An area nearly the size of New Orleans is already flooded downstream of Giacomzzi’s farm. State officials warned more water will come as warmer temperatures cause record snowpack to melt in the Sierra Nevada. This week, however, they said some communities, like Corcoran, should be spared from increased flooding due to levee improvements, favorable weather and efforts to distribute water upstream.

But capturing the extra water is an opportunity Giacomzzi worries he’s missing.

“The condition we’re in right now is there’s billions of gallons of water flowing through us, right next to us, heading down and filling Tulare Lake,” Giacomazzi said, referring to the lake. Long dry, once the largest west of the Mississippi River, which has come to life during storms this winter.

California water officials strive to trap as much floodwater as possible. In January, as a series of atmospheric rivers battered the state with rain and snow, the state Department of Water Resources announced it was expediting permitting for projects that return water to aquifers.

“Projects that capture available rainfall, stormwater or floodwater to recharge depleted groundwater basins must be prepared to capture high flows when available during each rainy season,” said Karla Nemeth, the agency’s director.

Two months later, California Governor Gavin Newsom signed an executive order making it easier for farmers to divert water onto their land.

But in some parts of the Central Valley, like Giacomazzi’s, bureaucracy, water rights and a history of overpumping are creating obstacles.

“The problem with these water systems in California is that every couple of miles in this state, it’s a completely different situation operated independently,” Giacomazzi said. “There’s really no coordinating body that sits on top if it says, ‘This is what we need to do. Let’s do it together.'”

A test for California’s climate future

California has always experienced dramatic swings from drought to flood. Those changes are expected to become more severe as temperatures rise due to human-caused climate change.

In that sense, the situation unfolding in California this year could be a window into the state’s climate future, said Daniel Mountjoy, director of resource management for Sustainable Conservation, a California-based nonprofit water group. “I’ve worked on water my entire career and one of our sayings is never waste a good crunch,” he said, standing next to a field of purposely flooded grape vines at a vineyard north of Fresno. “This is our chance to make everyone aware of what is possible.”

California water experts like Mountjoy, hydrologists and environmental watchdog groups have long warned that groundwater use in the Central Valley was unsustainable. Parts of the southern Central Valley that are now flooded have sunk as much as 28 feet in recent decades, deflating like a burst balloon because too much water has been pumped out of the ground.

The state intended to address the problem with 2014 legislation requiring local water agencies to balance their underground accounts.

“We’re going to have to put in as much as we pump,” said Eric Holder, a University of California irrigation research assistant.

Reducing groundwater use could be painful. A study last year by the Public Policy Institute of California found that approximately 500,000 acres of farmland would have to go unplanted in the southern Central Valley over the next 20 years to help restore groundwater. That’s even with higher stormwater capture in a year like this. The region produces billions of dollars worth of almonds, pistachios, dairy, and other products each year.

“We have to find a safe landing pattern,” Mountjoy said. “Think of a way to reduce pumping or increase groundwater supply.”

Some farmers are flooding their fields With much of the state inundated with water, the focus in California is increasing the supply of groundwater, adding more to the bank account, flooding farmland.

In some areas, like Giacomazzi’s, there aren’t enough incentives for farmers to flood their fields, or the infrastructure to divert water from canals and streams isn’t in place.

“It takes a lot of money to dig out a basin and build the structures to divert water from the system,” said Mark Larsen, general manager of the Kaweah Delta Water Conservation District. “And then you have him sitting [dry] most of the time waiting for a year like this”.

In some water districts, like Madera County, in the heart of the Central Valley, farmers are being encouraged to use their existing infrastructure to flood their fields with free or reduced-price water.

“That’s our way of encouraging people to take that water, distribute it and put it in the ground when it’s available in years like this,” said Thomas Greci, general manager of the Madera Irrigation District.

Nick Davis, who owns a vineyard with his twin brother on the outskirts of Madera, has decided to get involved. He has been pouring water on his vines since the heavy rains began this winter, sinking into the ground more than 4 times the amount of water he normally uses on the vines.

“We’re all skeptical about trying new things,” Davis said. “But we think it’s important to just do our part and put it back in the ground.”

He’s hoping the state will give him credit for all the water he’s returning to the aquifer, or pay him for the water he’s deposited. Incentives like that, Davis said, would make other farmers think more seriously about flooding their fields now and in future wet years.

“We understand that we are part of the problem,” Davis said. “But we also want to be part of the solution when possible.” [Copyright 2023 NPR]