Eastern Black or Prairie swallowtail (Papilio polyxenes asterius)
Ice Age National Scientific Reserve Unit, Wisconsin, USA
2015-09-12 216aaaa.jpg
Death of the Colorado River:
"PAGE, Ariz. — The first sign of serious trouble for the drought-stricken American Southwest could be a whirlpool.
It could happen if the surface of Lake Powell, a man-made reservoir along the Colorado River that’s already a quarter of its former size, drops another 38 feet down the concrete face of the 710-foot Glen Canyon Dam here. At that point, the surface would be approaching the tops of eight underwater openings that allow river water to pass through the hydroelectric dam.
The normally placid Lake Powell, the nation’s second-largest reservoir, could suddenly transform into something resembling a funnel, with water circling the openings, the dam’s operators say.
If that happens, the massive turbines that generate electricity for 4.5 million people would have to shut down — after nearly 60 years of use — or risk destruction from air bubbles. The only outlet for Colorado River water from the dam would then be a set of smaller, deeper and rarely used bypass tubes with a far more limited ability to pass water downstream to the Grand Canyon and the cities and farms in Arizona, Nevada and California.
Such an outcome — known as a “minimum power pool” — was once unfathomable here. Now, the federal government projects that day could come as soon as July.
Worse, officials warn, is the remote possibility of an even more catastrophic event. That is if the water level falls all the way to the lowest holes, so only small amounts could pass through the dam. Such a scenario — called “dead pool” — would transform Glen Canyon Dam from something that regulates an artery of national importance into a hulking concrete plug corking the Colorado River.
Anxiety about such outcomes has worsened this year as a long-running drought has intensified in the Southwest. Reservoirs and groundwater supplies across the region have fallen dramatically, and states and cities have faced restrictions on water use amid dwindling supplies. The Colorado River, which serves roughly 1 in 10 Americans, is the region’s most important waterway.
The 1,450-mile river starts in the Colorado Rockies and ends in the Sea of Cortez in Mexico. There are more than a dozen dams along the river, creating major reservoirs such as Lake Powell and Lake Mead."snip
"Buschatzke has also been raising the alarm about Lake Powell reaching dead pool — an elevation 120 feet below the threshold for producing power."
“It is a possibility. I can’t tell you the probability,” he said. “But that’s an outcome that would be not only an ecological disaster, but the world would have its attention on such an outcome in a very negative way.”
If that happens, “you’re not going to have a river,” he added. “It would be a catastrophe for the entire system.”
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“Officials fear ‘complete doomsday scenario’ for drought-stricken Colorado River”
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