The writing's on the wall. Article: The drought in US south-west is the worst in 1,200 years. It might be here to stay by Kim Heacox.
Heacox writes:
John Wesley Powell, the one-armed US army civil war veteran who led the first white expedition down the Colorado River through the Grand Canyon – a daring boat run in 1869 – later became an ethnographer who wrote a prescient 1878 government paper titled: Report on the Lands of the Arid Regions of the United States. In it, he unflinchingly described the scarcity of water, and summarized that much of the American south-west, if it must be settled, should be settled lightly and modestly. Overpopulate it, and it will be unforgiving.
People came anyway:
Decades later, the US Bureau of Reclamation oversaw the construction of two massive arch-gravity concrete dams on the river: Hoover Dam in the 1930s that impounded Lake Mead; and Glen Canyon Dam in the 1960s, that impounded Lake Powell.
And:
When the Bureau of Reclamation planned and designed the dams, they were warned that their data sets were too small; that the desert has moods, that rivers fluctuate, water comes and goes, and the bones of previous civilizations are everywhere.