As Southern Nevada grows, so will it's water needs. Conservation will help. But you just can't expect tourists and Las Vegas residents to give up their lawns, pools, golf courses, artificial lakes, artificial waterfalls, and all their other luxury evaporative loses.
Water is opulence in the desert. Water is status. Water is a sign of nature defying power. It's no surprise that Las Vegans don't want to believe that wasting water in the desert is somehow morally wrong. Don't be surprised either, that when they start to fear for their lifestyle; Las Vegans might be capable of rash, even desperate decisions.
I used to be a lifeguard at a pool in Las Vegas. And one thing I have learned from sitting around a swimming pool, is that a drowning person will drown anyone within reach... for a breath of air. It doesn't matter how irresponsible the victim was. It doesn't matter if the person trying to save them deserves to live more than they do. It doesn't matter how guilty they'll feel later. They'll kill you to save their sorry ass... Desperation is an extraordinary emotion. What would normally seem unthinkable, suddenly becomes absolutely necessary.
The building of the pipeline network, and the almost definite desertification of Central Nevada once seemed insane. Las Vegans fought it, and stopped it, for a while. But now that the Lake Mead water level is low, desperation seems to have set in, and they're willing to pay for it now.
Will the world support Las Vegas for doing this? Hell no! Will the tourists keep coming? If they know that by using the water and spending their money there, it would mean contributing to the destruction of the Central Nevada environment and the draining of the aquifers under the Desert National Wildlife Area and the Great Basin National Park, they obviously won't be as inclined to visit.
Customers don't like doing business with thieves – and that's just how some tourists will view Southern Nevada with this water grab. Customers don't like doing business in disgusting places, like wastelands, which Nevada will likely become without water. Just consider this; If you could go to an Indian casino and help out the Native Americans, why would you go to Las Vegas and help out the people who took the water from the Paiute and the Western Shoshone and left them unable to stop their native homeland from becoming the biggest dump in the nation – which, of course, would be right next door to Las Vegas.
On the other hand, tourists would respect Las Vegas for building desalination plants on the ocean; using solar, wind, and tidal power generators. They might even see Las Vegas as a progressive city near a vast expanse of natural land – worthy of a visit.