Jun 13, 2024

Protecting water supplies through groundwater recharge

To help improve water availability, a number of Central Valley California growers are participating with the U.S. Department of Agriculture in a groundwater recharge program.

The pilot program, launched and administered through USDA Office of Natural Resource Conservation Service (NRCS) in Fresno County, works to recharge groundwater supplies by flooding crop fields.

The NRCS initiated the program in reaction to groundwater depletion becoming a significant resource concern. The trial is working mostly with permanent crops, including grapes. While NRCS has been testing groundwater recharge for several years, the pilot program began in the fall of 2023, said Dave Krietemeyer, an NRCS area engineer.

NRCS is working with 20 grower contracts, up from 15 in 2023, with four more recharge basins, higher than the sole basin before.

Krietemeyer works with the state’s numerous water districts, which operate differently. Participating water districts are in Fresno, Kern, Madera and Tulare counties, and include Chowchilla, Madera, Delano, Fresno, Tulare and Delano districts. Krietemeyer reports favorable grower interest.

“Some districts operate where they have winter flow deliveries based on their share of what’s in reserve behind dams,” Krietemeyer said. “Historically, irrigation districts’ objective is to deliver irrigation water, not so much with floodwater delivery. Because of SGMA, that is different today.”

“But now that we’re in the mess we’re in with shortages of water, districts are doing everything they can. Some districts, it’s putting on excessive irrigation water. We’re not trying to leach nutrients below the root zone and into the aquifer, but it’s really to recharge water into the water tables by applying winter flood water or excessive irrigation beyond the crop demand.”

Growers are offered a $100 an acre incentive, which can help support labor as growers must employ workers to ensure water doesn’t run outside the bounds of their fields. NRCS requires berms around outside edges, which most operations already have, he said.

Richard and George Matoian of Matoian Brothers in Fresno plan to flood their table grapes and pistachios. Richard said the farm planned to participate in 2023, but was unable to fully implement the program because of lack of floodwaters.

The grant money will help Matoian and other growers fund the labor and time investments needed to perform and monitor the recharge.

Even though Matoian is fortunate to have enough surface water available where he grows, he can’t utilize that surface water for flood irrigation because of managing any number of spraying crews that must be done, he said.

As the program’s rules require the grapes to possess no leaves on vines or trees during recharge, the December or January dormant season would be an opportune time for recharge. Matoian said he hopes to show other growers in the area that recharge can be accomplished during dormant season and that all growers can benefit from the program.

“My interest in this is I want to be part of the solution to help utilize excess water to help recharge the aquifer,” Matoian said. “Our neighbors who do flood irrigation are really doing everyone else a favor because whatever’s not used by the plant is able to go into the aquifer. But, we use drip, and are only putting enough water on there for what the plant needs and uses. I saw this as an opportunity for us during a time of the year that we don’t have people and tractors in the fields to be able to put some water in the ground.”

Matoian said his sandy loam ground is highly conducive to water infiltration and slowly makes its way into the aquifer. In preparation, Matoian mapped his fields and coordinated with the Fresno Irrigation District to use surface water for flood irrigation during the dormant season.

Krietemeyer expects practices employed in the pilots to become permanent next year and hopes to open the program to more California growers.

“It’s all about timing and placement,” Krietemeyer said. “With SGMA (the Sustainable Groundwater Management Act) and the declining groundwater tables, it’s very important. It’s another tool in the toolbox. These GSAs (Groundwater Sustainability Agencies) are reaching for anything and everything they can try to do to mitigate subsidence and declining water tables, while still being able to pump groundwater. In the process of trying to make water available, we don’t want to create a new resource concern, as in degrading the water quality.”

Passed in 2014, the Sustainable Groundwater Management Act established a new structure for managing California’s groundwater resources at the local level by local agencies. SGMA required GSAs to form in the state’s high- and medium-priority basins and subbasins. More than 260 GSAs in more than 140 basins were formed by SGMA’s initial planning milestone.

Matoian farms 130 acres of grapes and pistachios. The farm’s roots go back to 1928.

— Doug Ohlemeier