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Dam opens

False flood unleashed on Colorado River

March 26, 1996
Web posted at: 8:00 a.m. EST

From Correspondent Don Knapp

PAGE, Arizona (CNN) -- Officials at Glen Canyon Dam in northern Arizona are doing something they've never done before. They are intentionally flooding the Colorado River to try to improve the river habitat downstream in the Grand Canyon.

Early Tuesday morning, Interior Secretary Bruce Babbit opened the valve that is sending Lake Powell's waters spilling into the canyon -- simulating what was once a natural spring flood. (315K AIFF sound or 315K WAV sound)

The Grand Canyon slices through geologic time. Its stark features are carved from the red sandstone of the Arizona desert by a once wild and relentless river.

But the Colorado River is wild no more. It has been tamed, for the past three decades, by Glen Canyon Dam. The river's flow has been carefully measured to meet demands for electric power generated by the dam's turbines.

And that has changed the river -- and the way it relates to the Grand Canyon environment.

Grand Canyon area map

The week-long flood is an unprecedented experiment, but the Bureau of Reclamation's David Wegner says that scientific research has made it clear that river systems, like the Colorado, "need periodic disturbances."

In other words -- floods are to rivers what wildfires are to forests. A renewal.

The millions of tons of sediment that once came down the Colorado River into the Grand Canyon, now settled in the bottom of Lake Powell, behind Glen Canyon Dam. The result is that the water that comes through the dam is cold, clear, and steady.

That kind of river is good for trout, but not so good for the native -- and now endangered -- humpback chub and other threatened or endangered species.

Image of the River Flowing

And steady flows, say government scientists, erode the river's beach habitats, leaving warm, stagnant backwaters.

"That cold clear water looks beautiful," says Wegner, "but it's not."

Adding sediment back into the system, Wegner says, is the only way to correct the imbalance. And the only way to do that is with a controlled flood.

But not everyone is happy. Trout fishermen worry the experiment will damage a prized fishery. But there has been little organized opposition to the experiment.

Geoff Barnard of the Grand Canyon Trust applauds the experiment, calling it the first time a big power dam has been used for environmental purposes.

Image of the Grand Canyon

"It opens a new era of cooperation of various entities," he said. (153K AIFF sound or 153K WAV sound)

Some of the effects of the man-made flood will be known in a few weeks. It may take years to learn if the flooding will help restore the river's environment.

But if the flooding is an environmental success, researchers say other dams may eventually get the same treatment.


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