The administration of California Governor Jerry Brown hit back on Thursday against criticism that its drought conservation mandates apply to consumers but do not include the state's $45 billion agriculture business.

Pushback from top water regulators came in response to complaints from environmentalists that agriculture, which accounts for 80 percent of water used by humans in the most populous U.S. state, should also be required to conserve.

"Agriculture in California produces the food we all rely on," said Secretary for Natural Resources John Laird at a briefing on the drought in Sacramento. "Folks want to point fingers, but we're all in this together."

The state produces half of all U.S. produce, and nearly all of such crops as broccoli, almonds and walnuts, Laird said, and farmers have already experienced cutbacks in their water supply that last year forced them to fallow 400,000 acres (162,000 hectares) of cropland and lay off 17,000 workers.

Making water even harder for farmers to get could damage the state's economy and force up food prices, he said.

The controversy began bubbling up hours after Brown, a Democrat, ordered a 25 percent reduction in urban water use last week in California's first-ever mandatory cutbacks, standing in a dry meadow in the Sierra Nevada mountains to emphasize that there was no snow to melt in the spring to feed rivers and streams.

Urban water systems would have to persuade consumers to cut back watering lawns and flushing toilets or face fines, but farmers would be exempt, Brown said, sparking criticism on op-ed pages and social media.

The angry response has led farmers, struggling amid record high temperatures and low water allocations from state and federal suppliers, to feel besieged, said Paul Wenger, president of the California Farm Bureau.

"I'm getting so many calls from farmers saying, 'I feel like I've got a target on my back,' " Wenger said.

Heather Cooley, a water expert at the Pacific Institute think tank, said agriculture worldwide typically accounts for up to 80 percent of a region's water use.

"It takes water to grow food," Cooley said. California farmers have become more efficient, but still have room to improve, she said.