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Tim Hussin, Deseret Morning News
Media, scientists, government employees and other spectators watch water stream out of the tubes at Glen Canyon Dam Wednesday.

PAGE, Ariz. — As much as it's possible with a dam in the way, the Colorado River was "set free" Wednesday with the start of the Department of Interior's highly visible part of its "high-flow" experiment.

Interior Secretary Dirk Kempthorne relished the moment of being the one to turn a wheel and push a button that began what will eventually be a flow of about 41,000 cubic feet of water per second being released through the Glen Canyon Dam for 60 hours. The amount of flow is equivalent, he said, to turning on 1.8 million garden hoses at once or filling the Empire State Building in 20 minutes.

"You realize the enormous power of the water," Kempthorne told the Deseret Morning News afterward. "It gives you a glimpse of how powerful nature is."

Earlier in a speech at the base of the dam, Kempthorne described how the canyon habitat and river between towering cliffs of red Navajo sandstone and far south of the dam have changed since its completion in 1966 and why the high-flow experiment is needed.

The high velocity of water is supposed to disperse sand buildup on the river bottom, similar to the goal of the last experiment of this kind in 2004. Only now, researchers say, there is three times the amount of sediment waiting to be moved. Kempthorne said this experiment will transport enough sediment to fill in a football field that is 100 feet deep.

By Saturday the high flow will end and the monitoring of the experiment's effects will begin, lasting for months. About 100 scientists from around the world are involved in the research surrounding the $4.1 million experiment. As early as Sunday the visual impacts of the release should start appearing.

"Today we're here to set the river free once again," Kempthorne told a crowd made up of National Park Service people from Glen Canyon and Grand Canyon, along with officials from the Bureau of Reclamation and U.S. Geological Survey. "We are the stewards. It is our turn to do our part."

That stewardship role is pinned on the hope that the sand being relocated will land downstream along the Colorado's 277-mile path through the Grand Canyon, rebuilding eroded beaches along the way. The beneficiaries are supposed to be wildlife that will use new or restored sandbars and beaches, which are also visited by people for campsites and recreation during float trips.

Skeptics made up of anglers and those who make a living from the river below the dam have been concerned about the timing of the flow and its impact on fisheries. But officials say the river should recover quickly, and the impact on fisheries should be minimal. Those are opinions based on knowledge gained from two previous experiments in 1996 and 2004.

Former Park Service regional director John Cook said Tuesday more experiments and "hard science" are needed to either validate or invalidate the expected results of this week's release.

Bureau of Reclamation commissioner Robert Johnson and National Park Service director Mary Bomar called for continued experimenting toward balancing the need for water storage, power delivery and resource conservation.

"Our descendants 500 years from now should be able to enjoy the same awesome vista that you and I are enjoying here today — and the same wildlife and the same recreational opportunities that we are enjoying today," Bomar said.

Hundreds of archaeological sites along the river may also benefit from the extra sand that shows up on river banks downstream. Then, through a more natural process generated mostly by wind, the goal is to see the new sand act as a barrier against the elements to protect those irreplaceable sites.

Nature in the form of spring runoff, monsoonal rains and occasional flooding used to take care of all of that, so much so that most of the archaeological sites were not even visible in the 1960s. But by 1966 the 710-foot tall dam (about 583 feet of it is visible) was complete and water began filling in most of Glen Canyon and surrounding areas. Lake Powell formed, becoming a magnet for boaters and fisherman as well as a source of fresh water in the desert Southwest and hydroelectric power for thousands across several states.

U.S. Geological Survey director Mark Myers said Wednesday the dam now traps about 90 percent of sediment generated by tributaries and runoff upstream. This latest experiment is timed to coincide with sediment from tributaries below the dam currently feeding into the Colorado.

What's left of Glen Canyon below the dam is stunning, characterized by tall red-rock cliffs brushed by desert varnish and punctuated in places by natural amphitheaters where portions of cliff face have fallen away. Along the way there is evidence of human activity dating back thousands of years, glimpses into their lives left behind in petroglyphs, pottery shards and pieces of burned wood.

But south of the dam, over the years, the ecosystem and riparian habitat changed. The waters between the dam and Lee's Ferry, 15 miles downstream, turned clear with blue-green tones in certain light. Some of that green comes from the buildup of algae and rooted aquatic plants. Without the dam the river's color, in a more natural state, would be more brown or milky with sediment. Below Lee's Ferry right now those contrasting colors can be seen mixing where the Paria River and its major source of sediment feeds into the Colorado.

Through the decades the now-endangered humpback chub have retreated about 60 miles downstream from Lee's Ferry, where there is more hospitable habitat. Bighorn sheep, pictured in a panel of ancient rock art not far from the dam, still roam the riparian habitat and side canyons near the Colorado. Permanent and migratory waterfowl can be seen all along the 15 miles of shore between Lee's Ferry and the dam.

After the release, which is expected to cause Lake Powell's already low level to drop 1 to 2 feet, the lake is anticipated to eventually rebound this year by about 50 feet, mostly due to spring runoff from a well-above-average snow season in the surrounding area. In the meantime, tourists are encouraged to witness a part of ecological and environmental history.

"Obviously it's a really exciting event to watch these four tubes shooting a spray of water," said Kevin Schneider, spokesman for the Glen Canyon National Recreation Area. "People can drive down and take a look."

The spectacle of the dam's four jet tubes releasing water should be visible today and Friday, with the high-flow part of the experiment expected to end sometime late Friday or early Saturday.

E-mail: sspeckman@desnews.com