LAS VEGAS, Nev. — Few parts of the nation are drier than the Las Vegas Valley. Yet, like a circus performer catching bullets in his teeth, the city here flouts the terrors of the desert and has achieved its own sort of rowdy transcendence. 

Las Vegas "owes nothing to its surroundings," wrote historian Hal Rothman in his 2002 paean to the city, Neon Metropolis. Today, 1.7 million people — 70 percent of Nevada’s population — live in Las Vegas and its suburbs. Unlike more traditional Western resource-extraction economies, which reach far out into the countryside for their fuel, Las Vegas tends to generate its wealth in place: The city’s $60 billion-a-year economy is dominated by the service industry — casinos and tourism — and its environmental footprint is remarkably small.

In fact, as the city has grown, its economy has come to serve as a life-support system for much of the rest of the state: Thanks to Las Vegas, 10 of Nevada’s 17 counties are guaranteed a fixed amount of tax revenue from the state, far more than they actually generate themselves.

Las Vegas’ phenomenal success has led boosters such as Rothman, a University of Nevada, Las Vegas history professor, to tout it as a model for the New West. But the city’s economy, powerful as it is, is perched atop a precarious pedestal: A tiny slice of the Colorado River’s water.

That doesn’t particularly concern Rothman. "No American city has ever ceased to grow because of a lack of water," he wrote in Neon Metropolis, "and it’s unlikely that Las Vegas will be the first."

"The only genuinely determining factor in acquiring water," he argued, "is cost." And money, Rothman wrote, "is no problem in Las Vegas."

As if to prove him right, Las Vegas is now pushing forward with what will be the biggest groundwater-pumping project ever built in the United States: a $2 billion effort that will pump more than 58 billion gallons of water out of the ground every year. The project will reach far beyond the glitter of Las Vegas into the valleys of eastern Nevada’s Basin and Range country, ultimately extending as far north as the area around the high-desert town of Ely.

When the play of light across the Great Basin is just right, it reveals the pockets of water that seem to disappear in the glare of the midday sun: stingy seeps, shy rivulets that poke their way across the desert, great limpid pools of water bubbling into the light. Those are all mere hints of the watery treasure trove that lies beneath the entire area: An enormous aquifer that spreads across some 100,000 square miles of eastern Nevada and western Utah.

Las Vegas has always pushed the limits harder than any other place, because it has had to — and because it can. "When you’ve got a city the size of Las Vegas, that’s growing as fast as it is, it’s hard to estimate what’s going to be economically infeasible," says Mike Dettinger, a U.S. Geological Survey hydrologist who authored some of the first comprehensive studies of the aquifer. "Anything’s possible if you have a big-enough city at the other end of the pipeline."

Las Vegas may, however, have reached the tipping point, beyond which its continued growth can only come at the expense of the rest of the state. The groundwater project in the Basin and Range will pry open a place of tremendous biological diversity that includes Great Basin National Park, three national wildlife refuges, at least three state and five federally listed threatened and endangered species, and a host of rural farming and ranching communities. Tapping the aquifer could unravel the tenuous hydrologic, ecological and political equilibrium in the Great Basin, giving the lie to boosters’ claims that Las Vegas is the city of the future. And, ultimately, the water project may be a prelude to an all-out war for the waters of the Colorado River.

The fight building over Nevada’s groundwater might never have started, if not for a space-age nuclear weapons program. In the late 1970s — at the same time he was hoping to create a legacy as a champion of arms control — President Jimmy Carter backed the MX missile program, a plan to shuffle 200 intercontinental ballistic missiles between 4,600 shelters in the Great Basin. The shell game was essentially a bluff, meant to force the Soviets to the negotiating table or risk blowing their entire nuclear wad shooting missiles at empty bunkers.

To the rural Nevadans who were going to be on the receiving end of a project designed to draw Soviet fire, the MX program made less sense. Environmentalists, Indians, ranchers and academics allied to mount a fight that swept the state. Steve Bradhurst, who directed the fight against the MX program for the governor’s office, says, "Wherever you went, particularly in rural Nevada, you’d see stop signs … you’d see ‘STOP,’ and then people would paint on ‘MX’ underneath."

In 1981, Nevada Sen. Paul Laxalt, a close friend of and the campaign chairman for Ronald Reagan, prevailed upon the newly elected president to ax the program.

Although the program never put a single missile in the desert, the search for the water it would have required significantly advanced scientists’ understanding of the desert’s aquifers.