GRAND CANYON NATIONAL PARK, Ariz. — Four decades after one of the West's last big dams blocked the free flow of water into the wild recesses of the Grand Canyon, the Colorado still manages to roar through here like the granddaddy of Western rivers. But it has become the Hollywood version -- strikingly beautiful and in vital ways, fake.
With every passing year, the Grand Canyon's stretch of the Colorado River bears less and less resemblance to its former self. The fine, white sand beaches on which thousands of weary boaters unfurl their sleeping bags every summer are disappearing.
So are native fish species that have been in the canyon for millions of years. Millennium-old Native American burial sites are washing away with the eroding sands.
Without the scouring of regular flooding, the feathery green tamarisk bush imported to the United States in the 1800s is overrunning the river banks, and boulders washed out of side canyons are piling up in the main channel. The river's mythic rapids are growing more difficult to navigate and some may become impassable.
The 1963 completion of Glen Canyon Dam just upstream from the park is best known in environmental circles for drowning stunning canyon lands under the waters of Lake Powell. But its effects have also been traumatic in the downstream river corridor of the Grand Canyon, through the heart of the park.
A warm, muddy, violently unpredictable river that shaped the canyon's ecosystem for millions of years turned cold, clear, steady and aquamarine. It may match the romantic notion of a river, but it is utterly unnatural in this sunbaked cleft in the Colorado Plateau.
The damage has long been recognized. Congress in 1992 passed the Grand Canyon Protection Act, directing the Interior Department to devise ways of making the dam's water releases for generating hydroelectric power less harmful to the canyon environment.
But it is increasingly apparent that the modified flows, adopted eight years ago, haven't worked. The failure has deepened the pessimism of some experts that, short of taking down the dam, humans may not be able to offset the harm done by its construction.
"The Grand Canyon river corridor is getting nuked," said David Haskell, a retired National Park Service career officer who directed the Grand Canyon's science center from 1994 to 1999. "It's in the final stages of having the natural ecosystem completely destroyed and replaced with a man-made one because of the presence of the dam."
