Inherit the dust: The Colorado River is running out of water. No place will be more affected than the arid metropolis of Phoenix
No one knows exactly why, in the 14th century, the Hohokam abandoned Pueblo Grande and other settlements across the Salt River Valley. Two hypotheses (perhaps not mutually exclusive) are that the Hohokam were laid low by prolonged drought and that hundreds of years of relentless irrigation salinized the soil, which in turn led to a collapse in agriculture. … Today, Pueblo Grande lies at the heart of a sprawling 15,000-square-mile megalopolis with some 4.9 million residents, which for the better part of half a century has been among the fastest-growing metropolitan regions in the United States. Like the previous civilization over which it is built, Phoenix must rely on maintaining control of that most precious and fleeting of desert resources: water.