In most of the eastern Great Basin, there are two aquifers, one on top of the other. For more than a century, farmers have tapped the one closest to the surface, which is made up of water caught in the sand and gravel that has filled in the valley bottoms. But below that lies the real prize: the deep carbonate aquifer, so called because the water is contained within massive bands of limestone. Several million years ago, the geologic faulting that created Nevada’s Basin and Range province took what was then a 50-mile-wide band of limestone, broke it into splinters, and smeared it out across the Great Basin. The fractures in the rock are packed with water.

As part of its investigations for the MX program, the Air Force drilled a series of wells that reached down into the carbonate aquifer. Those wells soon became fodder for the kinds of legends normally associated with deranged conquistadors seeking cities of gold in the desert. Dettinger, the USGS hydrologist, says one MX well, north of Las Vegas, "hooked into some sort of crack that went God knows where, and it produced like crazy." After that, he says, "there was a tendency to imagine that if you put a well into the carbonate, it would just make water." 

Back in 1922, the seven states along the Colorado River met to negotiate the Colorado River Compact. The Compact divvied up the river’s water and came to serve as the foundation for a complex set of agreements and legal rulings known among water managers, with a sort of Ten Commandments reverence, as "The Law of the River."

At the time, Nevada (which, practically speaking, meant Las Vegas) had less bargaining power than any of the six other states — California, Arizona, Utah, Colorado, Wyoming and New Mexico. Las Vegas was just a miserable little rail stop back then, and in all the years since, the city has been bedeviled by one stark fact: It walked away from the negotiations with just 300,000 acre-feet of water per year, a measly 4 percent of the water in the Compact. (One acre-foot is about 326,000 gallons, or enough water for two homes in Las Vegas for a year.)

By the 1980s, when a string of record-breaking growth years began, Las Vegas was beginning to feel the pinch. In 1989, the metropolitan area, whose population was just shy of three-quarters of a million people, grew by more than 61,000 — an astounding 8 percent.

The same year, Vegas hired Patricia Mulroy as the general manager of what would become the Southern Nevada Water Authority (HCN, 4/9/01: The water empress of Vegas). Mulroy immediately made it a personal crusade to ensure that the city had enough water to continue growing. And on Oct. 17, 1989, she made her first move toward the Basin and Range. Mulroy filed water-rights applications with the state for over 800,000 acre-feet of groundwater — more than twice the city’s Colorado River allocation, and enough to supply almost 1.7 million new homes.

Rural Nevadans reacted as if they were under Soviet attack, filing more than 4,000 protests with the state engineer and assembling a legal team that included former Arizona governor Bruce Babbitt, who would go on to serve as U.S. secretary of the Interior.

In response, Mulroy turned her attention elsewhere, and put the project on hold. Over the next decade, Vegas proved itself more adept than any other city in the West at digging change out of the couch. The Water Authority worked to increase water efficiency in Las Vegas, and began offering a dollar-a-square-foot bounty to the city’s residents to rip out their lawns, an effort that has resulted in the removal of 64 million square feet of grass. The city has also perfected a watery sleight of hand to stretch its meager share of the Colorado as far as possible: It pumps far more than 300,000 acre-feet out of Lake Mead each year, but treats its wastewater and returns it to the reservoir for re-use by California and Arizona.

During the 1990s, Mulroy also began talking with the six other Colorado River states. She called for a "major rethinking" of the way the river is managed, and she courted the other states in an attempt to buy some of their water (HCN, 2/21/94: Las Vegas wheels and deals for Colorado River water). Mulroy won the ability to "bank" some water in Arizona for drought years, but her call for changes on the river met a cool reception — particularly from Colorado, which has long styled itself as the enforcer of order on the river.

At the time, Colorado was in an enforcing kind of mood. For more than 40 years, California had been using more than its share of the river. Finally, in the 1990s, Colorado successfully led the Upper Basin states — which also include Utah, Wyoming and New Mexico — in demanding that it stop (HCN, 5/21/01: Quenching the big thirst).

Las Vegas’ relentless growth was proving equally worrisome. In 2001 alone, the city added more than 90,000 residents. The Upper Basin began to talk about forcing Vegas to live within its Colorado River allocation; when Mulroy came knocking, asking for more water, the other states sent her home to deal with her own problem.

Mother Nature, meanwhile, was putting a finer point on things. A major drought had started on the river in 1999, and 2002 brought a frying-pan-to-the-head moment. That year, the Colorado River received only a quarter of its average runoff.

Mulroy says that when river managers ran computer models during the 1990s to predict the likelihood of drought, "there was zero probability that a drought of this magnitude would hit. Nobody anticipated it."

It was clear that Mulroy was running out of options. Once again, she turned her attention to the Basin and Range country, and the hundreds of thousands of acre-feet of water that the city had claimed.