By Lindsay Wise

The prairie wind buffeted Brant Peterson as he stood in a half-dead field of winter wheat.

In front of him, a red-winged blackbird darted in and out of a rippling green sea of healthy wheat.

Behind him, yellowed stalks rotted in the ground.

The reason for the stark contrast was buried 600 feet under Peterson's dusty boots: Only part of the field _ the thriving part _ had been irrigated by water pumped at that depth from the ancient Ogallala Aquifer, one of the largest underground sources of fresh water in the world.

"If not for irrigation that whole field would look like this," Peterson said, nudging the dead wheat with the toe of his boot.

But irrigation soon could end on Peterson's southwest Kansas farm. The wells under his land in Stanton County are fast running dry as farmers and ranchers across the Great Plains pump the Ogallala faster than it can be replenished naturally.

Three of his wells are already dry.

Within five years, Peterson estimates, he likely won't be able to irrigate at all.

The depletion of groundwater stores also is a problem familiar to farmers struggling with drought in California, where pumping for irrigation has put the state's Central Valley Aquifer under the most strain of any aquifer in the U.S., according to NASA satellite data.

But California also has surface water: reservoirs, lakes, streams, rivers, snow melt from the Sierra Nevada and a water transportation system.

Western Kansas' only significant water source is the Ogallala.

Unlike in California, where national headlines, severe water-use restrictions and images of cracked earth bear testament to the ravages of drought, the crisis unfolding on Peterson's farm and others like it across western Kansas is mostly invisible.

It's taking place underground, in a sparsely populated rural area _ out of sight, out of mind for most Americans.

The vast freshwater reservoir beneath the prairie formed 5 million to 10 million years ago as streams draining from the Rocky Mountains deposited water in the clay, sand and gravel beneath the Great Plains.

The water lay there undisturbed for epochs until enterprising homesteaders who settled the West discovered the liquid bonanza that would make their arid land bloom.

Now, in a geological blink of an eye, the Ogallala, which made the Great Plains the nation's breadbasket, is in peril.

The disappearing water supply poses a twofold danger. It could end a way of life in a region where the land and its bounty have been purchased by the toil and sweat of generations of farmers.

It also threatens a harvest worth $21 billion a year to Kansas alone and portends a fast-approaching, and largely unstoppable, water crisis across the parched American West.

With water levels already too low to pump in some places, western Kansas farmers have been forced to acknowledge that the end is near. That harsh reality is testing the patience and imagination of those who rely on the land for their livelihoods.

As they look for survival, farmers are using cutting-edge technologies to make the most efficient use of the water they have left. They're contemplating something almost unimaginable just a generation ago: voluntary pacts with their neighbors to reduce irrigation.

And many are investing their long-term hopes in an astronomically expensive water transportation project that isn't likely ever to be built.

The Arkansas River, which once flowed out of Colorado into western Kansas, is nothing but a dry ditch now, its riverbed reduced to a rugged obstacle course for all-terrain vehicles.

And average rainfall here is just 14 to 16 inches a year, nowhere near enough to replace the water that farmers draw from the Ogallala. Kansas enjoyed a rainier-than-normal spring this year, easing several years of drought conditions throughout the state. But the relief is temporary.

The storms that soaked the state in recent months won't alter the Ogallala's fate, experts say.

"I feel hopeful for California. If it starts raining and snowing, their problem may somewhat take care of itself until the next drought," said Daniel Devlin, director of the Kansas Water Resources Institute at Kansas State University. "Our problem is going to be here rain or shine."

That's because the recharge rate for the Ogallala in this part of Kansas is less than 10 percent. So for every 10 inches pumped out every year, less than 1 inch is replaced, even in the best conditions.

Once emptied, it would take 6,000 years to refill the Ogallala naturally.

Peterson has seen his own well yields drop by more than half since 2009. Back then, he could pump 5,400 gallons per minute from 15 wells. But Peterson had to rely heavily on the aquifer during the recent drought, when his farm received less than 7 inches of rainfall a year for four years.

Now those wells are pumping just 2,600 gallons per minute for the same acres, and the water must be drawn from deeper under the ground, driving up the cost of running electric- or gas-powered pumps.

"The only thing I can do to conserve is to cut back acres," Peterson said. "So my revenue stream, my whole operation, has been dinged pretty hard, and then drought on top of that. It's been brutal."

The Ogallala Aquifer supplies water for 20 percent of the corn, wheat, sorghum and cattle produced in the U.S.

It sprawls 174,000 square miles across eight states, from South Dakota to Texas, and can hold more than enough water to fill Lake Huron and part of Lake Ontario.

But for every square mile of aquifer, there's a well. About 170,000 of them. Ninety percent of the water pumped out is used to irrigate crops.

Over the years, there have been multiple attempts to address the rapid decline of the aquifer. Water rights holders in much of western Kansas had to install flow meters in all their wells starting in the mid-1990s. Soon all wells in Kansas will have to be metered. And the state government has stopped issuing new permits to pump water from the Ogallala in areas of western Kansas where water levels have dropped the most.

Now, Kansas Gov. Sam Brownback has pledged to make water policy a central pillar of his administration. The final draft of his 50-year "water vision" for the state, released in January, outlines an incentive and education-based approach focused on encouraging voluntary, coordinated conservation efforts by the farmers who have the most to lose by the aquifer's decline.

Ten miles east of Peterson's farm, in Grant County, Kan., Clay Scott parked his Dodge pickup on a country road and reached for his iPad. A few hundred feet away, a solar panel planted in a field of wheat powered a probe that measures soil moisture at different depths.

Right now the probe told Scott's iPad that he could hold off on watering the field. His sprinklers lay idle.

"People think that we waste our water out here," Scott said, "and we just kind of grin because we work so hard to use that water."

In addition to the soil moisture probes linked to his iPad, Scott consults satellites and radar data to track every shift in the weather and drop of rain that falls in his fields so he can minimize irrigation. He uses low-till techniques to preserve the soil and experiments with genetically engineered drought-resistant corn. He installed more efficient nozzles on his center-pivot sprinklers.

And he's trying out a new device called a "dragon line," which drags perforated hoses behind a center pivot to deposit water directly on the ground, reducing pooling and evaporation.

The effects of the depleted aquifer already can be felt on Scott's farm, where he's had to reduce irrigation by 25 percent.

"I've got three boys, and a couple of them have already talked very seriously about coming back to the farm, and I'd like them to have the opportunity and ability that I've had to grow crops and livestock, even in a drought," he said.

Scott's long-term hopes rest in the construction of an $18 billion aqueduct that would import high flows off the Missouri River to water crops grown in western Kansas.

As conceived by the U.S. Army Corps of Engineers, the concrete ditch would stretch 360 miles from east to west across Kansas with 16 lift stations and massive reservoirs on either end. The proposal was met with opposition _ and not a little ridicule _ by the legislature in Topeka, as state lawmakers struggled to close a $400 million budget hole.

"We're not working on it at this point," Earl Lewis, assistant director of the Kansas Water Office, said in an interview.

Missouri Gov. Jay Nixon dismissed the aqueduct as a "harebrained" scheme that would divert river water needed for barge traffic and municipal use. But in western Kansas, it doesn't seem like such a crazy idea.

"When they're flooding in the Missouri River and cities are sandbagging, it sure seems to us like we have an answer to their problems," Scott said. "Nobody wants to build a house and see it flooded; nobody wants to plant a field and watch it wither."