Floodwaters on farms help boost aquifers

The historically wet winter early this year motivated greater adoption of a water management strategy known as flood-managed aquifer recharge, or flood-MAR, in which excess flood flows are diverted onto farmland to boost depleted groundwater aquifers.

“We knew from the previous year, even in intense drought years, we have opportunities with these big storm events and need to do everything we can,” said California Department of Water Resources Director Karla Nemeth, addressing water managers, farmers, government officials and others, as part of the Flood-MAR Forum in Sacramento last week. “Our ability to respond to those kinds of intense rain events is becoming increasingly important.”

Pointing to atmospheric rivers that hit the state in January, Nemeth highlighted the executive order by Gov. Gavin Newsom that enabled farmers to divert water onto farmland for groundwater recharge, which also helped mitigate flooding impacts.

Taking advantage of wet conditions is important for the state, especially as local groundwater sustainability agencies, or GSAs, have until 2040 and 2042 to implement plans and projects to bring groundwater basins into balance, as required by the Sustainable Groundwater Management Act, or SGMA.

Tulare Irrigation District general manager Aaron Fukuda, who also serves as interim general manager of the Mid-Kaweah Groundwater Sustainability Agency, located in the critically overdrafted Kaweah subbasin, offered insight in how the GSA uses recharge as a strategy.

“This time last year, we were going into three years of drought. We transitioned three months later into what was unexpectedly a tremendously wet year and spent the next nine months recharging,” Fukuda said. “We’re beginning to learn a lot more about putting excess water out in our fields in the wintertime.”

He said farmers in the subbasin who accepted floodwater to recharge groundwater this winter experimented with different ways to apply water to fields and found that standing water did not harm pistachio or walnut orchards.

“Our growers really took to the idea that this (flood-MAR) is going to be part of their future of managing their groundwater supplies,” Fukuda said. “Our growers are learning through these tools to be their own recharge agents. Everybody is cooperating and participating and learning and building the knowledge base.”

To meet SGMA requirements, Fukuda said, time is of the essence.

“SGMA allows 20 years to come into compliance, but you only have four years to solve the problem because you only have four years in the hydrologic cycle where you’re going to get wet years,” he said. “I encourage everybody—dig deep and look at recharge.”

Offering her agricultural perspective as part of a panel on flood-MAR success stories, Stanislaus County farmer Christine Gemperle, who farms almonds near Turlock, noticed last December water traveling down a Turlock Irrigation District canal near her farm. After several years of drought, the water appeared when her trees were stressed and a neighbor’s well had gone dry, she said.

“I was thinking it wasn’t going to rain at all,” Gemperle said. “If I had an opportunity to recharge in my area to benefit my neighbor, well, I was going to do it. TID helped make that happen.”

By Jan. 12, she said she opened the gate and began flooding her sandy loam soil with water for recharge.

“We flooded approximately 40 acres three different times, and it still continued to rain over that entire period,” Gemperle said. “We applied approximately 44 acre-feet and we didn’t lose any trees, which is a miracle because we had some very violent and windy storms come through.”

Madera County farmer Mark Hutson, who farms in Chowchilla, discussed applying floodwater on 40-acres early this year for recharge. He said he paid $10 per acre-foot for water used for recharge but stopped the effort in June when the cost increased to $97 per acre-foot.

“I just can’t do it. I’m not making enough money. I need to stay in business to be sustainable,” Hutson said. “Being able to do flood-MAR, I can help my community with water quality and the environment.

“Recharge areas will benefit wildlife because it’s a management practice that I plan for, budget for, and get some sort of payment for, hopefully,” he added.

It is important that farmers embrace flood-MAR and put it into practice, Hutson said.

“Farmers should start diving in and practicing it so they can get better at it, expand on it, or help their neighbors expand on it,” Hutson said. “They should talk to their water districts about supplying water at an affordable cost so they can learn this management practice.”

Discussing environmental benefits of flood-MAR, Julia Barfield, program manager at The Nature Conservancy, described a multibenefit project for farmers and GSAs that creates habitat for migrating shorebirds.

“As recharge was going to be ramping up with SGMA implementation, we wanted to demo to water managers how they could include wildlife benefits in their recharge projects, so we part started piloting a multibenefit recharge approach,” Barfield said. “To create critical habitat for migrating shorebirds, we use a reverse auction system where we ask landowners to tell us how much it will cost them to create the habitat, and then we select the bids that give us the greatest return on investment.”

As part of a state agency panel on advancing groundwater recharge, Kamyar Guivetchi, manager of DWR’s Division of Planning, said conversations about using flood flows to recharge groundwater “really took flood-MAR out of a theoretical, ethereal kind of abstract concept to something that really can and has to happen in California water management going forward.”

The Flood-MAR Network formed action teams that worked on six topics to remove challenges and/or leverage opportunities, he said, adding, “Everyone recognized, why aren’t we recharging more of this water?”

Paul Gosselin, DWR deputy director for sustainable groundwater management, emphasized how winter storms offer local GSAs a great opportunity.

“Looking at the half a million acres of agriculture that may go out in the San Joaquin Valley through implementation of SGMA, maximizing what’s available for recharge is going to be really important to minimize that amount of ag land going out of production,” Gosselin said. “This is going to be a good balance for trying to minimize the impact, which is going to be pretty severe, but doing nothing would be catastrophic.”

Addressing barriers to flood-MAR, Erik Ekdahl, California State Water Resources Control Board deputy director of water rights, said his agency is viewed as a barrier in many circumstances. But he said that is the water board’s role.

“We are supposed to make sure that if there is water for diversion, that it can be safely and appropriately diverted and stored, or used for flood-MAR and recharge purposes,” Ekdahl said.

(Christine Souza is an assistant editor of Ag Alert. She may be contacted at [email protected].)

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