Will Western Cities Face a "Reverse Katrina"?

Ward warns in particular that the heavily dammed Colorado River is of particular concern, owing to numerous cities that depend upon it:

"If the Colorado River shut down tomorrow, there might be two, at most three, years of stored water in its massive reservoirs to keep Los Angeles, San Diego, Phoenix, Las Vegas, and dozens of other cities that depend on it alive. That margin for survival gets thinner with each passing year and with each rise in the average temperature. Imagine a day in the not so distant future when the water finally runs out in one of those cities -- a kind of slow-motion Katrina in reverse, a city not flooded but parched, baked, blistered, and abandoned...After decades of frantic urban development and suburban sprawl across the states that draw water from the Colorado, demand has simply outstripped supply and it's only getting worse as the heat builds."

Ward argues that Western Americans must become extremely conscious of their place in their watersheds and conserve water through xeriscaping and other means.