A research project announced Monday will look at whether almond orchards can help recharge groundwater in winters when river supplies are plentiful.
The Almond Board of California, based in Modesto, launched the project with Sustainable Conservation, a San Francisco group that helps farmers and other businesspeople protect the environment.
As part of the two-year effort, researchers will gather information from growers who have used excess surface water in wet years, such as 2010 and 2011, to replenish aquifers. And if such water is available this coming winter, they will soak selected orchard floors and let the moisture seep down.
“We really want to increase the supply and use all that space that’s underground,” said Daniel Mountjoy, director of resource stewardship at Sustainable Conservation, which has a Modesto branch office.
Almonds have become the top farm product in the Northern San Joaquin Valley over the past two years. Stanislaus County reported $1.35 billion in gross income last year, while San Joaquin County had $578.6 million; Merced has not yet reported.
The industry has faced scrutiny over its water use during a drought that is now four years old. Its backers note that most of the acreage now is on drip lines or microsprinklers, which use less water than flood irrigation. But they also claim that flooding the ground has boosted aquifers, providing backup supplies in dry years.
The researchers plan to test recharge on 10 farms around the San Joaquin Valley. Two of them already are part of a study by the University of California Cooperative Extension in Stanislaus County.
“It’s really figuring out how the almond industry can play a significant role in helping with groundwater management,” said Richard Waycott, the board’s chief executive officer.
River supplies have plunged with the drought, but the partners hope for above-average runoff this winter thanks to El Niño. The National Weather Service projects a 95 percent chance that this ocean-warming phenomenon will develop, although it does not always translate into more rain and snow.
The drought has left reservoirs low, but Mountjoy said they still have to make scheduled releases in winter to make room for possible heavy runoff in spring. Part of those releases could be captured in canals and provide the water for the recharge project.
The researchers also will look at whether the winter irrigation damages the trees. Mountjoy said orchards with poorly draining soil can develop root diseases, but this is less likely in the sandier ground where the recharge would take place.
The water would be applied during the trees’ dormant period, a few months after harvest and before the February bloom that starts off the next crop.
For more coverage of the California drought, please visit the Modesto Bee.
Top image: Jim Morris stands in a flooded alfalfa field in March 2015 in Siskiyou County. The field was intentionally flooded as part of a study by University of California scientists that proved heavy flood irrigation can recharge groundwater aquifers. Similar research will be conducted on San Joaquin Valley almond orchards this winter. (Steve Orloff)