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.