Farmer Jim Weddle turned off the water on some of his alfalfa fields last year. They didn’t stand a chance under the baking Arizona sun. Without water, the land is now as dry as the surrounding desert. Heat ripples off it in shimmering waves.

There would be no agriculture here on the mesa outside Yuma, Arizona without the waters of the Colorado River, stored behind the Hoover Dam 240 miles north. The farms form a tidy green grid against the great beige expanse of the Sonoran Desert.

But as Lake Mead shrinks, “you certainly worry about the future,” Weddle said. “The dams have been sustaining us for years, but they can only drop so far before there isn’t any more water to come out.”

There’s plenty of Colorado River water here now, despite the drought. It rushes through the lattice of concrete-lined canals that crisscross the fields of alfalfa and citrus.

And Yuma’s farmers are under no obligation to give it up. They have high-priority rights to that water under Western water law going back more than a century.

But the Southwest’s cities are eyeing a drier future. Since agriculture uses about four-fifths of the river’s water throughout the basin, cities are looking to farmers for help.

So a pilot program in Arizona is paying farmers like Weddle not to grow a crop — and to save some water.

Weddle says it’s a good deal, for now.

But while cities are asking for water today, he worries that tomorrow they will be taking it.

Authorities expect that as soon as next year, they will have to reduce water deliveries from Lake Mead for the first time ever.

Yuma’s farmers would still get their water. The cut would fall first on farmers upstream who get water from the Central Arizona Project, a 336-mile canal system that carries Colorado River water across the state.

But the impacts of the looming cut are already rippling down to Yuma.

The canals also deliver water to Phoenix and Tucson, the state’s two largest urban areas, and officials only give the cities 10 or 15 years before their Colorado River supplies are affected, too.

Cities looking to replace their losses see fallowing farmland as an attractive, if temporary, option.

“If there’s a significant shortage and it’s impacting cities,” said Tom McCann, assistant general manager of the authority that oversees the project, “maybe in that year you go and say, ‘Hey, can we pay you, the agricultural user, not to use water this year so that we could have it for cities?’”

The authority is backing the pilot program that pays farmers like Weddle not to grow a crop.

The program is too small to have much of an impact. The point is to find out how much water fallowing an acre of Yuma cropland would save.

A lot of people would like to know. Four major urban water authorities in Arizona, California, Nevada and Colorado that depend on Colorado River water plan to fallow more ground as part of an $11 million program aimed at propping up Lake Mead.

But the Yuma deal is short-term, and Weddle wants to keep it that way. Farmers are wary of giving up too much to keep the cities afloat.

Any talk of reallocating water raises red flags in Yuma. Agriculture is a big part of the local economy. Drying up farms could dry up local businesses, too, from tractor dealers and seed companies to grocery stores and restaurants.

Farmers have the law on their side. But as times get tighter on the Colorado and the big urban areas hunt for water, farmers are concerned that could change.

“Congress could step in [and] perhaps the state legislature might have something to say also,” said Yuma citrus grower Mark Spencer.

Even the pilot program makes people nervous, Weddle added. “Everyone’s certainly concerned, even if you do a small-scale program, if your water is going to come back. That’s a risk we’re taking. And that’s why this is a very short-term, small program.”

Farmers here are willing to do their part, Spencer said, but the fast-growing cities of central Arizona got themselves into this predicament.

“Maybe they’ve got to limit the number of houses that they can build, or the number of golf courses that they can put it, or the number of times that they can water their lawns,” he said.

But according to Phoenix water manager Kathryn Sorensen, the city has all the water it needs for the foreseeable future. The Colorado is a major water source for the metropolis, but not its only one.

“We’re not looking to ask Yuma to stop growing crops so we can grow houses,” she said. “Where we’re at is making sure we don’t run the system into the ground. And I think that there’s a collective risk for all of us in that.”

“We’re not looking to ask Yuma to stop growing crops so we can grow houses.” – Kathryn Sorensen, Phoenix water manager

Water will stop flowing out of Lake Mead if the level falls another 100 feet. That would be a disaster for Yuma’s farmers as well as for Phoenix, Sorensen added.

And Sorensen is aware of the risks fallowing poses to local economies. “Those things matter,” she said. “It needs to be done in a way that’s very sensitive to the community…and can provide some benefit to the local economy as well.”

To entice farmers to participate, the Central Arizona Project agreed to pay them $750 per acre per year to fallow their land. About 10 percent of the land on the Yuma mesa will be fallowed for the three-year program.

The commitment is small enough and short enough to satisfy the farmers. And it gives them a welcome opportunity to let their land rest. The Arizona desert sun bakes away germs that lurk in the soil. Crops planted after fallowing are more productive. But a fallow field generates no income. So getting paid for it is a bonus.

“It’s a sort-of symbiotic-type program here that’s a win-win for a lot of people,” Spencer said. He has 280 acres in the program. The money he earns is offsetting the costs of supporting young lemon trees elsewhere on his farm that are not yet producing fruit.

Weddle said farmers probably could have asked for more money, but, he added, “I feel the information right now is more important to get than to try to beat somebody up for how many dollars you can get.” Once they know how much water they can save, “then the marketplace will dictate the value of the water,” he added.

The marketplace already knows the water is valuable. A private company called Greenstone has bought land in Yuma and neighboring areas. Company executives declined to comment, but local farmers say Greenstone bought the land for the water rights. As the strain on the Colorado River increases, those rights may be more valuable than the land, and cities may be willing to pay good money for them.

That is, if the company can sell them. The Yuma mesa’s irrigation district, not the landowners, owns the water rights. The district’s board of directors would have to approve a sale.

And that’s not likely, at least not today. Weddle and Spencer are both board members, and neither supports the idea.

“I’m certainly against water farms, other cities or towns or even absentee owners coming in and buying large parcels of property and trying to dry up 100 percent of that ground,” Weddle said.

But investors seem to be betting the situation will change.

Some kind of change is likely, Spencer says. Water probably will get more expensive. Growers probably will need more efficient — and more costly — irrigation systems. Alfalfa for animal feed is a major commodity here, but such a low-value crop may not make sense anymore.

“But one thing people have to realize,” Weddle said, “if they’re going to have milk, if they’re going to have steaks, they’re going to have to have alfalfa.” And, he added, it’s better to grow it on the marginal land of the Yuma mesa, rather than using up prime farmland elsewhere.

The Central Arizona Project’s Tom McCann counters, “Is it more valuable to have a pasture that an animal can wander around in or to have a vibrant city?”

Cities or farms? As water gets tighter, everyone who depends on the Colorado River will have to decide what is most valuable.

But there’s one silent stakeholder that’s been ignored for most of the last century. As humanity has tapped the river to the limit, there is a growing recognition of the devastation inflicted on natural ecosystems. And there are indications that attitudes are beginning to change.