Sin City's Continuous Flow

You could almost hear the clang of jackpot bells in Pat Mulroy's office. In late April, the tenacious water czar of southern Nevada chalked up another win in her two-decade crusade to satisfy Las Vegas's unquenchable thirst. This time it was thanks to a state water regulator's thumbs up on a plan to pump almost 20 billion gallons of water from a vast underground aquifer near the state's east central ranchlands, sucking water from deep beneath its hayfields and sending it 285 miles south to the quarter of a million homes served by Mulroy's Southern Nevada Water Authority.

he decision was followed days later by an even bigger coup: a historic agreement to rejigger the way Colorado Riverwater is divvied up among Nevada and the six other western states that share the lifeline. Swapping the current use-it-or-lose-it annual system for a more flexible, market-style approach, the hard-fought deal among the states marks the biggest change in the controversial "Law of the River" since it was inked some 80 years ago. It lets downriver states like Mulroy's create liquid bank accounts, allowing them to save up surplus water in wetter years, in reservoirs for instance, to use during later periods of drought, and also lets them bolster their water supplies, in part, by paying for other states to conserve, so more water might be available for Nevada—a scheme that is expected to win final approval from Interior Secretary Dirk Kempthorne by year's end.

more from US News and World Report