Last spring, as he stood at the base of Arizona’s Glen Canyon Dam and prepared to initiate a man-made flood on the Colorado River, Interior Secretary Bruce Babbitt proclaimed a new era in management of the most important dam and river in the American Southwest.
Glen Canyon, he said, would help repair some of the environmental damage it had caused downstream in the Grand Canyon since it was constructed in the 1960s.
Somebody forgot to tell Mother Nature.
With an unusually heavy snowpack building up in the Rocky Mountains, the dam’s operators this week will begin releasing large volumes of water from Lake Powell that some scientists believe could wipe out many of the environmental gains achieved from last spring’s man-made flood.
At risk, the scientists say, are the beaches and backwater habitats partly restored by the man-made flood.
“I suspect a majority of the beaches created last year are going to end up eroding and washing downstream,” said Dave Wegner, who headed the environmental study that led to the “beach-habitatbuilding test flow.”
Last year’s seven-day flood on the Colorado, which culminated a 15-year, $60 million environmental study, was designed to mimic - on a reduced scale - the periodic floods that roared down the Rockies and through the canyon country of the desert Southwest.
In its natural state, the Colorado was a flood-driven river, with spring runoff depositing huge amounts of sand along its banks, creating beaches, sandbars and habitat for all kinds of creatures, including several species of now-endangered fish.
Recognizing that taming the river was damaging the canyon’s ecosystem, federal authorities in 1991 set out to re-create the periodic spring floods with last year’s experiment.
The idea was to stir up millions of tons of sediment on the bottom of the river and deposit it on the banks as the flood tapered off.
“This marks a sea change in the way we view the operation of large dams,” Babbitt said last year. “We have shown they can be operated for environmental purposes as well as water capture and power generation.”
But even as Babbitt was speaking, the first snows of winter were blanketing the western slope of the Rocky Mountains, which drain into the Colorado River basin. Bureau of Reclamation officials now estimate the basin’s snowpack and runoff will be 171 percent of normal.
That inflow, on top of what is already there, would overflow the dam unless releases begin soon.
Grand Canyon National Park senior scientist Bob Winfree fears the releases could increase the mortality of young endangered fish like the humpback chub, flood habitat needed by the endangered willow flycatcher bird far downstream, and harm the rare and endangered Kanab Ambersnail.
The releases also could reduce camping opportunities for the thousands of whitewater rafters who annually float the Colorado.
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