When Marc Reisner updated his landmark book Cadillac Desert in 1992, he mistakenly referred to the "forceful woman" who heads the Las Vegas-based Southern Nevada Water Authority as Patricia Mulwray. Her name is actually Patricia Mulroy.

Reisner's mistake might have been a Freudian slip: Hollis Mulwray is a character in the movie Chinatown who is based on William Mulholland, the powerful founder of the Los Angeles Department of Water and Power. Mulholland occupies a special place in the pantheon of Western water honchos, as both visionary and villain. He is best remembered for his audacious, and very secret, plan in the 1920s to buy up water rights in the Owens Valley and ship the water to L.A.

Mulroy understandably bristles at any reference to Chinatown. Yet she has achieved a degree of power that might even make Mulholland envious. Mulroy has largely set the terms of Western water over the past two decades. She has challenged what she calls the conservative "belt-and-suspenders" mindset that has traditionally prevailed among Colorado River water bosses. And, most controversially, she has led a two-decade-long effort to build a massive groundwater project that will tap huge aquifers lying beneath the Great Basin in eastern Nevada and pipe billions of gallons of water to Las Vegas.

This August, the state governments of Nevada and Utah announced that they had put one more piece of the project into place. They released an agreement that divides the water beneath the Snake Valley, on the Nevada-Utah line, between the two states, and that also delays for a decade the legal formalities needed to complete that final part of the groundwater project.

The announcement touched off a furor in Snake Valley. "We only got about a week's notice, and it left us scrambling to try to understand the agreement," says Mark Ward, an attorney for the Utah Association of Counties.

The agreement apportions the remaining water in Snake Valley 7-to-1 in Nevada's favor and "practically eliminates future development in Snake Valley," says Kathy Walker, the chairman of the Millard County Commission. Since the agreement was released, she says, "we've been racking up some serious miles" in an effort to change the terms of the deal. 

Some pipeline opponents, however, see the agreement as a reprieve of sorts. Denys Koyle, who owns the Border Inn casino on a lonely stretch of Highway 50 on the Nevada-Utah border, says, "When I saw it, I thought, ‘Oh my gosh: We've got 10 more years.' I've been saying every day we buy is a big victory."

The hoopla over the most recent development in the groundwater saga obscures a larger reality. Patricia Mulroy has tackled the groundwater project with far less secrecy than William Mulholland would have used. Still, over the past three years, she has moved to lock in the water she needs for the project with remarkable finesse. The Southern Nevada Water Authority now has at least 37 billion gallons of water lined up for the project, which will span seven valleys on the east side of Nevada, from Coyote Springs Valley to Spring Valley, and Snake Valley on the Nevada-Utah line.

"We already have the necessary water rights to go all the way to Spring Valley," says Mulroy.

But even as the Water Authority has amassed the permits it needs to fill the pipeline with water, unsettling questions have emerged regarding the project's impacts on desert springs ecosystems. And one of Mulroy's own scientists says her agency is hiding the effects that groundwater pumping will have on the Great Basin.