The greatest water crisis in the history of civilization: coming to the American West?

Consider it a taste of the future: the fire, smoke, drought, dust, and heat that have made life unpleasant, if not dangerous, from Louisiana to Los Angeles. New records tell the tale: biggest wildfire ever recorded in Arizona (538,049 acres), biggest fire ever in New Mexico (156,600 acres), all-time worst fire year in Texas history (3,697,000 acres).

The fires were a function of drought. As of summer’s end, 2011 was the driest year in 117 years of record keeping for New Mexico, Texas, and Louisiana, and the second driest for Oklahoma. Those fires also resulted from record heat. It was the hottest summer ever recorded for New Mexico, Texas, Oklahoma, and Louisiana, as well as the hottest August ever for those states, plus Arizona and Colorado.

Virtually every city in the region experienced unprecedented temperatures, with Phoenix, as usual, leading the march toward unlivability. This past summer, the so-called Valley of the Sun set a new record of 33 days when the mercury reached a shoe-melting 110º F or higher. (The previous record of 32 days was set in 2007.)

And here’s the bad news in a nutshell: if you live in the Southwest or just about anywhere in the American West, you or your children and grandchildren could soon enough be facing the Age of Thirst, which may also prove to be the greatest water crisis in the history of civilization. No kidding.

If that gets you down, here’s a little cheer-up note: the end is not yet nigh.

In fact, this year the weather elsewhere rode to the rescue, and the news for the Southwest was good where it really mattered. Since January, the biggest reservoir in the United States, Lake Mead, backed up by the Hoover Dam and just 30 miles southwest of Las Vegas, has risen almost 40 feet. That lake is crucial when it comes to watering lawns or taking showers from Arizona to California. And the near 40-foot surge of extra water offered a significant upward nudge to the Southwest’s water reserves.

The Colorado River, which the reservoir impounds, supplies all or part of the water on which nearly 30 million people depend, most of them living downstream of Lake Mead in Los Angeles, San Diego, Phoenix, Tucson, Tijuana, and scores of smaller communities in the United States and Mexico.

Back in 1999, the lake was full. Patricia Mulroy, who heads the water utility serving Las Vegas, rues the optimism of those bygone days. “We had a fifty-year, reliable water supply,” she says. “By 2002, we had no water supply. We were out. We were done. I swore to myself we’d never do that again.”

In 2000, the lake began to fall -- like a boulder off a cliff, bouncing a couple of times on the way down. Its water level dropped a staggering 130 feet, stopping less than seven feet above the stage that would have triggered reductions in downstream deliveries. Then -- and here’s the good news, just in case you were wondering -- last winter, it snowed prodigiously up north in Colorado, Utah, and Wyoming.

The spring and summer run-off from those snowpacks brought enormous relief. It renewed what we in the Southwest like to call the Hydro-Illogic cycle: when drought comes, everybody wrings their hands and promises to institute needed reform, if only it would rain a little. Then the drought breaks or eases and we all return to business as usual, until the cycle comes around to drought again.

So don’t be fooled. One day, perhaps soon, Lake Mead will renew its downward plunge. That’s a certainty, the experts tell us. And here’s the thing: the next time, a sudden rescue by heavy snows in the northern Rockies might not come. If the snowpacks of the future are merely ordinary, let alone puny, then you’ll know that we really are entering a new age.

And climate change will be a major reason, but we’ll have done a good job of aiding and abetting it. The states of the so-called Lower Basin of the Colorado River -- California, Arizona, and Nevada -- have been living beyond their water means for years. Any departure from recent decades of hydrological abundance, even a return to long-term average flows in the Colorado River, would produce a painful reckoning for the Lower Basin states. And even worse is surely on the way.

Just think of the coming Age of Thirst in the American Southwest and West as a three-act tragedy of Shakespearean dimensions.

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We have already experienced close to 1º C of that increase, which accounts, at least in part, for last summer’s colossal fires and record-setting temperatures -- and it’s now clear that we’re just getting started.

The simple rule of thumb for climate change is that wet places will get wetter and dry places drier. One reason the dry places will dry is that higher temperatures mean more evaporation. In other words, there will be ever less water in the rivers that keep the region’s cities (and much else) alive. Modeling already suggests that by mid-century surface stream-flow will decline by 10% to 30%.

Independent studies at the Scripps Oceanographic Institute in California and the University of Colorado evaluated the viability of Lake Mead and eventually arrived at similar conclusions: after about 2026, the risk of “failure” at Lake Mead, according to a member of the Colorado group, “just skyrockets.” Failure in this context would mean water levels lower than the dam’s lowest intake, no water heading downstream, and the lake becoming a “dead pool.”

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