Viva Las Vegas, with your neon flashin'
And your one-arm bandits crashin'

All those hopes down the drain.

Viva Las Vegas, turnin' day into nighttime

Turnin' night into daytime
If you see it once
You'll never be the same again.
– Elvis Presley, 1964

J.C. Davis pilots a white sedan through a late-vintage planned community about 10 miles southeast of the Las Vegas Strip. Nearly empty streets curve gently past architectural features tinted the bland beige shades mandated by each development – a khaki wall here, tan homes there, a sand-colored CVS pharmacy – like lithium for the eyes. Just past a biscuit-colored Starbucks, Davis parks on a street that, for now, marks the dividing line between suburbia and open desert. Here, workers put the finishing touches on a row of closely snuggled, nearly identical stucco houses, colored – you guessed it – beige, and capped with trendy tan tile roofs.

From the passenger seat, I gaze in bafflement. Ostensibly, Davis, the gregarious, clean-cut public information officer for the Southern Nevada Water Authority, is here to show me a "Water Smart" home. I had pictured a one-off prototype that would never really be lived in – some sort of rammed-earth, recycled-cardboard affair complete with composting toilet and a hairy, unwashed tenant.

Instead, I get Inspirada, a new-urbanist community conceived in 2004, when houses were sprouting in southern Nevada at a rate of more than three per hour. On 1,900 acres bought from the Bureau of Land Management for $577 million, a consortium of developers planned 11,500 homes arranged in seven "villages," each with its own theme. The community was meant to evoke pre-World War II America, with a town square, parks and a boutique casino. Yet even as the Desert Mermaids frolicked in a community pool and an American Idol star belted out "The Star-Spangled Banner" during the 2007 grand opening, the whole "build it and they will buy" credo was evaporating under the desert sun. The Southwestern housing market twirled into free fall, and Inspirada's developers ultimately went bankrupt with less than 700 homes built. But with the market making a sputtering comeback, Inspirada is reviving.

Every house that national builder KB Homes erected in the development is part of the Southern Nevada Water Authority's voluntary Water Smart program, meaning it uses an average of just 94,000 gallons annually – about half the water guzzled by older Las Vegas homes, and 20 percent less than those of similar vintage. "Short of living in a high-rise, it's about as efficient as you're going to get," says Davis, whose organization, composed of seven districts, manages water for some 2 million people in the greater Las Vegas metro area.

This is sustainability, Sin City style. It sounds like a bad joke. After all, this is the place visited by 39 million people yearly, all of whom gobble ghastly amounts of carbon-spewing fossil fuels to drive or fly here. This is where, for just $250,000, you can push the button that makes a 22-million-gallon fountain ejaculate, or play one of 61 iridescently green golf courses scattered across the sprawl in a region that gets 4.2 inches of rain annually. Here, urban revitalization involves stringing a canopy of 12.5 million lights over a city street, creating a seizure-inducing display whose effects can be tempered only with the help of 96-ounce cocktails. Don't worry; the drinks are cleverly designed to hang around your neck, keeping your hands free for playing slots and smoking.

"Vegas and sustainability are two words that don't typically come together in most people's minds," admits Las Vegas Sustainability Director Tom Perrigo in what may be the diplomatic understatement of the year. But lately, this paragon of excess has been making noteworthy strides in both the public and private sector, from the city government pledging to make its collective facilities "net zero," to resorts embracing LEED-certified construction.

Of course, the real test for the nation's driest city is water. Ninety percent of the Vegas metro area's supply comes from the nearby Colorado River, which is shackled by a 14-year drought. The hard limits to decades of conspicuous consumption are clearly visible just 30 miles from the city, where Lake Mead – a reservoir on the river – is so low that a hundred vertical feet of its craggy banks are exposed. Even as the Water Authority scours far and wide for new sources, it has also quietly cultivated an old-fashioned alternative: efficiency.

Beyond Inspirada, my tour takes me to a wastewater treatment facility that, after removing all the crap, sends clean water back out to golf courses and parks. I sit down with a group of nerdy engineers – rock stars in their field – whose job it is to find and plug leaks in the 4,100 miles of water lines below the city, saving hundreds of millions of gallons each year. At a golf course, I try to talk green speeds and turf lengths with a course superintendent who ripped out acres of grass. And I see first-hand just how much fat some of the mega-casino resorts have managed to cut from their energy and water budgets.

Ultimately, I find evidence that the city is, indeed, becoming vastly more efficient and may even be inching towards so-called sustainability. And it's not in spite of the raw and uninhibited consumption that has made Vegas a legend, but, ironically, because of it.