Last May, Donald Trump stood in an arena full of farmers from California’s desiccated Central Valley and said words many yearned to hear: “If I win, believe me, we’re going to start opening up the water.”

The audience, waving FARMERS FOR TRUMP signs, hollered their approval.

“I just met with a lot of the farmers,” he said. “They have farms up here and they don’t get water. I said, ‘Oh, that’s too bad. Is it a drought?’ ‘No, we have plenty of water.’ I said, ‘What’s wrong?’ ‘Well, we shove it out to sea.’ And I said ‘Why?’”

“They’re trying to protect this three-inch fish!” Trump said incredulously.

At the mention of the three-inch fish, the audience booed.

Trump was repeating an argument used by California’s agricultural industry for decades: That the region’s water woes are not caused by nature, but by regulations. Specifically, those that under certain circumstances keep water in California’s rivers rather than diverting it to farmlands, in the name of protecting a “three-inch fish” — the delta smelt — and other native species that are threatened with extinction.

Environmental regulation is widely scorned in California’s productive and politically muscular Central Valley. Four-hundred miles long and framed by a pair of mountain ranges, the valley counts among the most fertile lands in the world, producing a quarter of the nation’s food and much of the state’s $50 billion agricultural output.

But California’s fickle weather leaves the valley in constant peril of losing its lifeblood, water. Until this winter, the state was suffering an historic drought — the worst in a millennium, by one measure. Some farmers went two years without receiving any water from public channels. To cope with the scarcity, some farmers with private wells have pumped water so aggressively that their land is sinking. Others simply stopped growing things: Half a million of California’s 7 million acres of farmland went fallow for want of hydration.

This season’s heavy rains have raised hopes that the worst has passed. But nobody expects California water politics to recede with the drought.

Though California is a famously blue state, its agricultural heartland beats red. This is slowly changing as the valley diversifies and urbanizes. But like so many other rural areas in America, the region decisively voted for Trump in the general election: He beat Hillary Clinton in 13 of the valley’s 19 counties, winning those counties by an average of 18 percentage points.

“Twenty or 30 years ago, the press always wrote about northern California versus southern California,” said Richard Frank, director of the California Environmental Law and Policy Center at the University of California at Davis. “That’s an outdated model. If there are two Californias, they are coastal California and inland California. The Central Valley really is Trump country.”

Farmers don’t see eye-to-eye with the new president on everything: His stance on immigration worries an industry dependent on migrant labor. And his withdrawal from the Trans-Pacific Partnership trade deal with Asian and Pacific nations is a disappointment for agribusinesses who ship their products abroad.

But for farmers in the Central Valley, nothing governs business success more than water, and for many, his promise to “start opening up the water” is a source of optimism.

Precisely how he will do that is up for debate, since the federal government’s role in California’s water politics is not all-powerful. The federal government owns and operates the infrastructure that delivers most water to farmers in the Central Valley. But the state can limit how much water that system distributes through a permitting process and other regulation.

Aubrey Bettencourt, a third-generation farmer, executive director of the pro-agriculture nonprofit California Water Alliance, and a participant in the conversation that Trump had with farmers prior to his May rally, listed two ways she hopes the Trump administration will influence California water politics.

First, she said, it can be more assertive in negotiations with the state about how to distribute water. “The last administration very much stayed out of the way and allowed the state to fill that void,” she said.

Second, she said, it can overhaul the federal government’s environmental programs and policies.

In that, Central Valley farmers appear to have Trump’s support. In addition to the promises he made in his two trips to the valley during his campaign, as president he has vowed to “massively” cut regulations on business. “We think we can cut regulations by 75 percent. Maybe more,” he told business leaders on the Monday after his inauguration. A week later, he issued an executive order requiring agencies to remove two existing regulations for every new rule introduced, and capped the cost of new regulations.

Among the regulatory targets in many farmers’ sites is the Endangered Species Act, which has proved a critical legal tool for environmentalists and fishers who wish to keep water in rivers rather than sending it to farmland.

The act was approved nearly unanimously by Congress in 1973. It became a source of fury for many California farmers when it was deployed during the state’s 1987-1992 drought, said Holly Doremus, a professor of environmental regulation at the University of California at Berkeley. Both the delta smelt and chinook salmon were listed under the act, and for the first time, water that could have gone to farmers was left in rivers specifically to keep a species extant. Courts upheld the restrictions, despite lawsuits filed on behalf of agribusiness.

It was around then that the concept of “regulatory drought” caught hold. Today, billboards sport the phrase throughout the valley. Farmers generally acknowledge that the Central Valley’s rivers and their delta are in sorry shape, but argue that restricting water to agriculture isn’t the way to save an ecosystem. While both state and the federal biologists have issued opinions that diverting more water from rivers would be harmful to species, agribusiness advocates often note that the Endangered Species Act has been keeping water in rivers for 25 years, and the species are more threatened than ever.

“I’m not arguing that we shouldn’t be trying to save our species and environment,” said Bettencourt. “But when the programs we’ve implemented are not seeing results, when we don’t require that accountability, how are we ever going to know what’s working?”

But, Doremus said, the Endangered Species Act was never intended as a plan to make species’ thrive — just to give them the bare minimum to survive.

“In many ways, the Endangered Species Act is a last-minute emergency room law. It’s supposed to provide a respirator before the patient is actually dead,” she said.

Environmentalists say farmers often exaggerate the influence of the Endangered Species Act on water distribution. It is more common for water to be kept in rivers because to do anything else would make California’s tap and irrigation water salty — an outcome undesirable for everyone, said Kate Poole, a senior counsel at the Natural Resources Defense Council. Agriculture is already responsible for 80 percent of the human water use in California. The remainder goes to cities and manufacturing uses. After a period in which millions of Californians faced restrictions on water use, environmentalists argue that farmers should focus on using the water they have more efficiently, rather than lobbying for more.

But agriculture is key to the Central Valley, and farmers say that while they are eager to see infrastructure and efficiencies improved, their immediate priority is getting their fields back in business.

“Most farmers would tell you, ‘I don’t want to see fish die. I don’t want to fight with environmentalists. I just want to go back to work,’” Bettencourt said.

This argument has sway not just with Republicans, but with some Democrats who have agricultural constituents. In December, Sen. Dianne Feinstein (D-Calif.) sponsored a bill signed by President Barack Obama ordering as much water as possible to go to California farmers without pushing endangered species into extinction. The reach of the new law will almost certainly be hammered out in court, but many conservationists see it as a short-sighted move that erodes the power of the government to protect ecosystems.

Phil Isenberg, a former Democratic state representative and retired vice-chair of the Delta Stewardship Council, said that even though everyone in California’s water politics arena is anxiously watching Trump, it might be a long time until anything changes.

“It’s probably fair to say that crafting a coherent water policy for California is number 9,764 on their priority list,” Isenberg said.

Bettencourt acknowledged that revamping the Endangered Species Act is not likely Trump’s highest priority. But, she said, it’s still a comfort for many farmers to know that in their fight for more water, they have an ally in the White House.

The rains this year have been a blessing for all parties, as near-empty reservoirs return to normal levels and rivers overflow. But the rains have also highlighted other problems: The lack of adequate water storage in a state sure to be beset by drought again and again, exacerbated by climate change and rising population. Though water is abundant after this years floods, scientists say these pressures will force farmers to adjust to a world where water will continue to be scarce — regardless of regulation.

This story is part of an investigation from Frontline called “How The Deck Is Stacked: The realities of getting ahead in the new American economy.” You can read the original story here.

Other stories in this series:

Can President Trump keep his promises to coal country?

Can President Trump bring back manufacturing jobs?