Jae C. Hong, Associated Press
In this May 1, 2014 file photo, fourth-generation rice farmer Josh Sheppard walks across the dried-up ditch at his rice farm in Richvale, Calif.

FRESNO, Calif. — Farmers in pockets of California hardest hit by the drought could begin to see their wells run dry a year from now if rain and snow remain scarce in the agriculturally rich state, according to a study released Tuesday.

Richard Howitt, a University of California, Davis professor emeritus of agriculture and resource economics, urged farmers to take the lead in managing groundwater to irrigate crops and sustain California's $44.7 billion farming industry.

Farmers are accustomed to having a seemingly endless supply of water, Howitt said.

"My message to farmers is treat groundwater like you treat your retirement account," Howitt said in an interview. "Know how much water's in it and how fast it's being used."

The study released by the University of California, Davis, Center for Watershed Sciences, used computer modeling, NASA satellite data and estimates provided by state and federal water agencies to examine the impact on California if the next two years continue to be abnormally dry.

Howitt and his colleagues presented the research at the National Press Club in Washington, D.C.

California leads the nation in production of more than a dozen crops, including almonds, artichokes, grapes and peaches. However, the study estimates that this year farmers will leave nearly 430,000 acres unplanted, or 5 percent of total irrigated cropland, costing the California economy $2.2 billion and more than 17,000 jobs.

Agriculture makes up less than 5 percent of the state economy, which Howitt said sounds minor, but the losses will hurt farming communities in the Central Valley.

The drought is not driving up food prices because farmers are shifting toward high-valued crops grown primarily in California — such as almonds — and away from those grown more widely such as cotton, Howitt said.

To nourish those crops, farmers have been pumping more groundwater as the mountain snowpack sends less water to state reservoirs and canals. The groundwater is not being replenished.

California is the only western state that doesn't measure groundwater use, and Howitt said demanding more of wells is a short-term solution with long-term costs.

"It's very simple economics, but it's such an emotional topic," Howitt said. "Farmers have to sit down and ask themselves... do they want their children and grandchildren to be farming?"

The California Department of Food and Agriculture requested the research.

Karen Ross, the department's secretary, said she recognizes the critical state of California's groundwater and the need for local officials to manage it. If that does not happen, Ross said the state will intervene.

Millions of Californians depend on ground supplies for drinking water, she said, adding that farmers have a large role to play.

"It's not if there will be future droughts," Ross said in an interview. "There will be future droughts, and we need to take our lessons and prepare ourselves as much as possible."

Jay Lund, director of the UC Davis Center for Watershed Sciences, said he doesn't anticipate a rainy El Niño next year to rescue California. As a result, the state needs to implement a variety of measures, such as conservation and managing groundwater and reservoirs, he said.

Paul Wenger, president of the California Farm Bureau, said losses attributed to the drought could have been avoided if state leaders had added more reservoirs rather than focusing for decades on conservation.

He also said the Farm Bureau has long supported groundwater management at a local level.

"Statewide regulation certainly won't fix our groundwater needs, just as it has failed to provide solutions to surface water needs," he said.