SACRAMENTO, Calif. » California’s almond orchards have been thriving over the past decade and now provide an $11 billion annual boost to the state economy. Covering 860,000 acres, they account for 80 percent of world production. But the growth coincides with another record development here – drought – and the extensive water needs of nut trees are posing a sharp challenge to state water policy.

Farmers in the area where almond production has been most consistent have relied on water from a federally controlled project that draws its supply largely from the Sacramento River. But that source is less reliable because of legal requirements that in a time of scarcity, waterways that nurture California salmon must also get available water flows.

Growers, some very wealthy, tried to get Congress to change those rules but failed. Also, new state groundwater legislation may eventually constrain farmers’ well drilling.

Almonds "have totally changed the game of water in California," said Antonio Rossmann, a Berkeley lawyer specializing in water issues. "It’s hardened demand in the Central Valley."

Farmers are planting almonds because, as permanent crops, they do not need to be replanted after every harvest. They have been steadily taking over from cotton and lettuce because they are more lucrative.

"That’s the highest and best use of the land," said Ryan Metzler, 45, who grows almonds near Fresno.

The problem is that not only do almonds and pistachios, another newly popular nut, need more water, but the farmers choosing permanent crops cannot fallow them in a dry year without losing years of investment.

Now the state is putting new controls on the groundwater that has gotten many farmers through the brutal drought – which still looms over the state, despite recent rains – and there is no certainty that the future of almond and pistachio orchards in areas like the western San Joaquin Valley is secure.

So almond growers are determined to be granted the water they need to keep their crops from dying, particularly in the Westlands Water District in the San Joaquin Valley, where 15 percent of the fields are covered with almond trees, up from 5 percent about 15 years ago. They chafe at the rise in the 1990s of environmental restrictions designed to help the survival of salmon species threatened by two generations of water diversions.

"We’ve had 20 years of a regulatory approach that has not improved the fishery," said Jason Peltier, the chief deputy general manager of the Westlands Water District, which serves some of the richest growers in the state. "The reality is that their regulatory methods have failed on every measure" of the health of salmon species.

His hope for the next Congress is that "they will take a look at the social and economic damage that the regulatory environment has created out here."

The assertion that environmental laws hurt farmers and farm laborers has proliferated during three years of searing drought, when federal water allocations were almost completely cut off. The claims infuriate opponents who feel that satisfying Westlands’ demands would hurt other more valid claimants.

"They are hurting other farmers, people, communities and industries," said Rep. Jared Huffman, a Democrat whose district along the north coast includes many fishing interests. "There are big-time winners and big-time losers here."

The proposals in the failed legislation – which was sponsored by Rep. David Valadao, R-Hanford, in the southern San Joaquin Valley agricultural heartland – "would upend a whole number of laws" and long-established priority rights to surface water, said Kate Poole, a water expert with the Natural Resources Defense Council.

She added, "We have clearly exceeded the ability of our water supplies – including surface and groundwater – to meet the demands we’re putting on it. We have to change, stretching how much we can get out of each drop through expanded urban and agricultural efficiency."

But, she said, "the Republicans in Congress seem to want to go in the other direction and upend the centuries-old priorities and give water to more politically powerful wealthy interests."

Almonds are thriving not just in the western San Joaquin Valley, but across the state.

Dino Giacomazzi, a fourth-generation dairy farmer in Hanford, is changing the makeup of his land. About 40 percent of his 1,000 acres – currently used for pasture or for alfalfa and other crops to feed cows – are being converted to almond fields.

Almond trees are far more difficult to plant than field crops like hay – "It takes 40 guys a day to do 20-40 acres," as opposed to one man plus a tractor to plant 100 acres of hay – but the diversity of agricultural efforts will make his business more secure, he believes.

"The trees and dairy can support each other at different times," he said.

A new almond farmer to the north is Shane Tucker, who is 54 and started out in the business of financing agricultural enterprises. Then, with an eye to raising his young children in the country, he decided to start farming in Davis in Yolo County.

He started with walnuts. About five years ago, he figured that water constraints would limit almond expansion in the drier San Joaquin Valley, and "prices were going to go up." Northern almond growers, he said he believed, would have a leg up. He planted almonds in 2013; he expects his first crop next year.

Tucker predicted that "irrigated surface water is going to become less available" in areas south of the delta that lie just east of San Francisco Bay.

"The economic impact on almonds is going to be significant," he added.

Growers in the drier parts of the San Joaquin Valley are served either by federal or state water projects that date to the mid-20th century. The drought forced these project managers to make draconian cutbacks in 2013 and 2014, prompting anger among all growers, particularly the new almond and pistachio barons.

"They do believe it’s their right to have access to water," Tucker said. "Yeah, they are angry. Potentially their livelihoods are threatened."

© 2014 The New York Times Company