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Amid strong storms, California turns to farmland to channel water to depleted aquifers


As storms have drenched Northern California, diverted water from the swollen Sacramento River has been flowing from a canal and spilling onto 200 acres of farmland.

For more than a month, the water has spread across the fields, forming shallow pools and then slowly seeping into the earth.

This farm northwest of Sacramento, which previously produced rice, is being used to replenish groundwater. It is one of a growing number of sites in the Central Valley where landowners and local water managers are using farmland to take advantage of this year’s heavy rains and snowfall by capturing water and putting it underground.

Once applied to fields near the town of Dunnigan, the water quickly sinks into the ground, working its way through the sediments to the aquifer. Measurements in nearby wells show that groundwater levels have risen.

American avocets feed on a flooded farm in Yolo County.

(Carolyn Cole/Los Angeles Times)

“Within a couple of days, we see an improvement in the water table,” said David Schaad, a farmer and president of the Dunnigan Water District. “It’s wonderful to see it.”

Seeking to encourage similar efforts throughout California, Governor Gavin Newsom recently signed an executive order suspending permit requirements for groundwater recharge in many areas. He order, Running through June 1, it will make it easier for local water districts and farms to route river flows to fields and other sites where water can push depleted aquifers.

The push to use farmland to recharge managed aquifers has been praised by experts who say it can help the state combat overuse and become more resilient as climate change unleashes more intense droughts and floods.

But some have criticized the governor and state water regulators for what they see as a lack of planning. They say the current rush to flood farmland risks washing harmful pollutants into aquifers, and more work is needed to identify the most suitable properties for recharge.

Much of the Central Valley was once a vast floodplain fed by the rivers that flow from the Sierra Nevada. Many areas of the valley that once flooded and allowed water to seep naturally into aquifers have been transformed into farmland, crisscrossed by networks of canals and levees.

Geese rest and feed in a flooded agricultural field.

Snow geese rest in a flooded field near Dunnigan, where farmers are part of a project to recharge groundwater aquifers.

(Carolyn Cole/Los Angeles Times)

Decades of over-pumping from agricultural wells have left groundwater severely depleted in much of the Central Valley, leading to subsidence or subsidence of soil, causing damage to canals and other infrastructure. Falling water levels have also left rural residents with dry wells.

State officials say projects like the one in Dunnigan can begin to address long-term water deficits.

“This is how we’re going to start to recover from the drought, reclaim the water in our drought buffer, our storage bank,” said Tim Godwin, policy and technical adviser in the Department of Resources’ Office of Sustainable Groundwater Management. state water. . “It’s important that when we have excessive flows, we replenish these systems, so that when the next drought hits, we’re prepared and can weather those conditions.”

For its recharge effort, the Dunnigan Water District has received “surplus” water from the Sacramento River from the Tehama-Colusa Canal. Some of the water has been released into a stream to replenish the aquifer; other flows have been routed to the privately owned farm.

A man is standing by a stream.

Bill Vanderwaal, general manager of the Dunnigan Water District, is working with farmers to replenish aquifers.

(Carolyn Cole/Los Angeles Times)

“If we can take surface water when it’s available and put it in the ground, that’s good stewardship of the land, of the aquifer,” said Bill Vanderwaal, district administrator.

Even before winter storms, the Dunnigan Water District secured water last year to flood fields in an effort focused on replenishing groundwater and creating habitat for shorebirds.

“When we started flooding that field, the birds were there like this,” Vanderwaal said, snapping his fingers. “You could see all the white egrets.”

The district obtained water for that project with help from the Nature Conservancy, which has been supporting groundwater recharge efforts that also create shallow-water habitat for migratory birds.

A white bird flies over the water.

An egret flies over fresh water on flooded farmland in Yolo County.

(Carolyn Cole/Los Angeles Times)

“This is a great example of what we need to do more of,” said Rodd Kelsey, associate director of the Nature Conservancy’s water program in California. He said the goal should be to “spread that water over tens of thousands, if not hundreds of thousands, of acres.”

Measurements at wells near the farm show water levels have risen 35 to 40 feet since October, Vanderwaal said.

“It’s coming into the aquifer much faster than I imagined,” Schaad said. “It’s amazing.”

The inflows to the aquifer promise to increase water levels in home wells and surrounding farms that produce almonds, tomatoes and grapes.

In other parts of the Central Valley with permeable soils, growers have invested in infrastructure to send stormwater to vineyards and orchards, successfully replenishing groundwater while continuing to grow crops.

Newsom has called for increasing the amount of water used to recharge aquifers as part of his plan to adapt to more extreme conditions with climate change.

To that end, the State Water Resources Control Board recently approved a plan to divert floodwater from the San Joaquin River to replenish groundwater in agricultural areas. The state Department of Water Resources says it has given local water agencies $68 million to support 42 recharge projects.

A man stands in the middle of flooded farmland.

Researchers at the Public Policy Institute of California estimate that by 2040, the average annual supply of water for agriculture could decline by 20%.

(Carolyn Cole/Los Angeles Times)

In many areas, agricultural irrigation districts have already built basins where water can be channeled to recharge groundwater. Agricultural water district leaders have focused on replenishment as a way to ease the required cuts in pumping they will face by 2040 under the state’s Sustainable Groundwater Management Act.

The researchers warn that even if California succeeds with more recharges, it won’t provide enough water to eliminate severe deficits in areas where aquifers are overdrafted.

Studies have projected that large portions of the Central Valley’s irrigated farmland will need to be left dry to comply with groundwater law. Researchers at the Public Policy Institute of California estimated in a recent report that by 2040, the average annual water supply for agriculture could decrease by 20%. They estimated that up to 900,000 acres of farmland may need to be left fallow.

The governor’s order is a positive step, said Helen Dahlke, a professor of integrated hydrological sciences at UC Davis. She hopes the order can help “trigger a new movement to review what system we have in place to divert these high flows to recharge groundwater.”

The current regulatory system is cumbersome and bureaucratic, requiring water agencies to hire consulting firms and lawyers, Dahlke said. Many applications are denied the first time, she said, and it usually takes months for an agency to approve a permit.

Dahlke said he hopes state officials will speed up the process. The system should strike a balance between maintaining river flows necessary for the environment and replenishing aquifers, she said.

Snow geese on flooded farmland.

Snow geese winter in warm parts of North America, then head north in the summer.

(Carolyn Cole/Los Angeles Times)

“Really taking advantage of those wet years when they happen is key to securing more water for future years,” Dahlke said. “We have a groundwater aquifer that can absorb three times the amount of water that we can store in surface water reservoirs, and it is protected from evaporation.”

The Central Valley is more than 8 million acres of irrigated farmland they are well connected to canals and can serve as expansion grounds while allowing agriculture to continue, Dahlke said.

“It is a very cheap method. It is probably the cheapest we can think of in terms of water storage and management,” he said.

Dahlke said the state should set a goal of recharging 1 million to 1.5 million acre-feet of water during wet years, about two to three times Los Angeles’ total annual consumption.

The state is still far from that goal. The State Water Board says that, since December, it has approved the diversion of about 790,000 acre-feet for groundwater replenishment, as well as supplies for wildlife refuges.

Some water advocacy groups criticized the governor’s order, saying that while they agree on the importance of recharge, they are concerned that a lack of oversight could lead to flooding of fields where contaminants in the soil could reach the aquifer. . They cited concerns about nitrates from fertilizers, which pose a health hazard and already contaminate wells in many rural areas.

“Once a groundwater basin is contaminated, it typically takes at least decades to clean it up,” said Michael Claiborne, managing attorney for the Leadership Counsel for Justice and Accountability group. “It is very, very expensive. And in our rush to get water into the ground, we need to make sure that we’re not doing it so that we can’t use the water that’s already there.”

The governor’s order includes some protections, including a ban on recharging on dairy land, but Claiborne said the protections don’t go far enough. His group, along with Clean Water Action and Community Water Center, urged state officials plan so that the next time heavy flooding is available, they have detailed maps showing where recharge can be done safely to protect drinking water.

Karla Nemeth, director of the Department of Water Resources, said state officials are aware of areas where potential water quality problems exist and will work to ensure that it is recharged in “the right places that will allow us to protect water quality.”

With the heavy rains and heavy snowfall, the governor’s order sends a signal to encourage landowners and water districts to capture floodwater and store it underground, Nemeth said.

“It is crucial for the future of the valley to get this groundwater recharge going,” he said. “And I think agriculture has an important role to play.”

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