Almonds have claimed the spotlight as “the poster child of all things bad in water,” almond grower Bob Weimer said.

People around the world are eating over 1,000 per cent more California almonds than they did just a decade ago, and last year almonds became the top export crop in the nation’s top agriculture state.

China’s booming taste for California almonds is producing up to 30 percent returns for investors, prompting agri-businesses to expand almond planting in the state by two-thirds in the past decade. The crop has come to be dominated by global corporations and investment funds.

California growers provide 80 percent of the global supply of almonds. In China, where the number of middle-class households has doubled since 2006, consumers see almonds as a healthy snack and regard American food in general as less contaminated than products from elsewhere.

California almonds are a popular bagged treat in China’s convenience stores and supermarkets and a must-have item in holiday gift baskets.

Rows of almond trees now cover nearly 400,000 hectares in California, many of them on previously virgin hillsides or in pastures or desert with little rain or local water. Since each tiny nut requires about 4 litres of water, almonds are consuming 4 trillion litres annually in the state, one-fifth more than all California families use indoors.

So when Governor Jerry Brown ordered cities and towns this month to cut their water consumption by 25 percent but exempted farms, almonds got toasted in the public heat that followed.

“Drought villains?” the Los Angeles Times asked this month. A Sacramento TV station referred to “almond-shaming.” National Public Radio called almond farms “a rogue’s gallery” of water users.

Now almond farmers and investors are on the defensive.

“The tomato growers use a lot more water than we do. You should go after those guys,” said Ryon Paton, a global real-estate developer and principal of Trinitas Partners.

Paton’s online literature tells investors to think of his newly planted almond orchards in Stanislaus County as “the classic Silicon Valley startup, except we have nothing to do with technology.”

As big a global money-maker as California’s agriculture is, though, it’s little more than a blip in the state’s economy. And that’s driving the debate on water use.

In all, agriculture uses 80 percent of the water that Californians draw from groundwater and surface supplies but produces just 1.5 percent of the state’s gross domestic product, noted Christopher Thornberg, an economist who has served as an economic adviser to state agencies.

Other top almond producers include Stewart and Lynda Resnik, the politically influential Beverly Hills billionaires behind Fiji bottled water, Pom pomegranate juice and a Central Valley almond and pistachio operation that they say is one of the world’s largest.

Smaller almond farmers view the newer, bigger almond investors sceptically.

“They shouldn’t be growing almonds or walnuts in those areas,” including parts of the state that are naturally too dry and too cold for almond trees, said Paul Wenger, head of the state Farm Bureau and an almond and walnut grower on land near Modesto that’s been in his family for a century.

Almonds aren’t even the biggest sponges when it comes to water-thirsty crops in semi-arid California — that would be the state’s 400,000 hectares of alfalfa, which goes to feed livestock.

But unlike the row crops they’re displacing, new almond trees require water year round.

The governor and his cabinet secretaries defend almonds as a high-value crop.

“We’re going to try to maximise all beneficial uses, not pick one we like better than the others,” said Felicia Marcus, head of the state Water Resources Control Board.