Federal officials say many farmers up and down the Central Valley will receive no irrigation water this year from their system of canals and reservoirs.
The U.S. Bureau of Reclamation says it will continue to monitor rain and snowfall, but at this point, allocations will drop to zero.
The feds say that water used by communities and wildlife will also suffer deep cuts.
California officials who manage the state's other vast water system, have already said they won't be releasing any water for farmers.
"We have been talking with our growers and it appears that we will have approximately 200,000 acres that will lie empty," said Gail Holman, with the Westlands Water District, which serves 700 family farms in Fresno and Kings Counties.
Tens of thousands of acres of rice crops could go unplanted in Sacramento. Urban customers will also see reduced allocations
Keith Watkins, of Bee Sweet Citrus, in Fowler, Calif., says no water means some farmers might have a tough decision by the end of May.
"We're going to have to make a call whether or not we're going to start removing permanent plantings of citrus -- navel oranges, lemons, mandarins," he said.