"Feds' plans to 'flush' Grand Canyon stirs concerns"

From the LAtimes

The Grand Canyon is about to take a bath, and National Park Service officials who oversee the natural wonder are worried.

Federal flood control managers, led by Interior Secretary Dirk Kempthorne, this week plan to unleash millions of cubic feet of water from behind Glen Canyon Dam to "flush" the huge canyon bottom with a simulated springtime flood.

Bureau of Reclamation and U.S. Geological Survey specialists say the 60-hour "blowout," followed by a series of smaller flows this fall, are needed to scour accumulated sand off the Colorado River bottom, then gradually restore sandy beaches and side pools for endangered species and campers.

The flows begin today, and a massive release is set for Wednesday in a media event with Kempthorne.

At its peak volume, 41,500 cubic feet per second of water will burst from tubes at the bottom of the dam, temporarily reducing flows to hydroelectric turbines. The experiment will not affect power or water supplies to customers, officials said.

National park officials said that 10 years of research at a cost of $80 million had shown that the flooding as planned could irreparably harm the national park's ecology and resources.

Grand Canyon National Park Supt. Steve Martin said he was given a day to formulate comments to a cursory environmental assessment of the project. In those comments, he wrote that statements by the Bureau of Reclamation used to justify the flows' timing were "unsubstantiated." Far from restoring crucial sand banks and other areas, the flows could destroy habitat, Martin said....

Erosion has been a major problem since Glen Canyon was dammed for hydroelectric power and water storage in the 1960s. Congress passed the Grand Canyon Preservation Act in 1992 to address ecological problems caused by holding back massive amounts of sediment-laden spring runoff.

The first flush of the Grand Canyon, in 1996, was a mixed success at best, scientists concluded, with some spots more eroded than they were before.

A second flush, in 2004, was slightly more successful, restoring sand and sediment levels about 20 miles downstream of the dam...