March 6, 2008

Grand Canyon's deluge by design

A man-made flood is unleashed from a dam near the Utah border in hopes of restoring the area's ecosystem.

From the Associated Press

PAGE, ARIZ. -- Torrents of water roared from the base of the Glen Canyon Dam in northern Arizona on Wednesday as federal authorities unleashed a man-made flood designed to help restore the Grand Canyon's ecosystem.

More than 300,000 gallons of water per second were being released from Lake Powell above the dam near the Arizona-Utah border, enough to fill the Empire State Building in 20 minutes, Interior Secretary Dirk Kempthorne said.

"This gives you a glimpse of what nature has been doing for millions of years, cutting through and creating this magnificent canyon," Kempthorne told the Associated Press after he pulled the lever releasing the water.

The water gushed from two of four giant steel tubes in parallel arcs into the Colorado River below. By the afternoon, water poured from all four tubes, creating a churning, frothy pool beneath the salmon-colored sandstone walls of the sheer-faced canyon rising hundreds of feet above.

The Colorado's water level rose by a couple of feet in some places and as much as 15 feet in narrower parts. After the flood ends Friday, officials hope the water will leave behind sediment and restore sandbars as it goes back to normal levels.

Before the dam was completed in 1964, the Colorado River was warm and muddy, and natural flooding built up sandbars that are essential to native plant and fish species. The river is now cool and clear, its sediment blocked by the dam.

Officials have created a flood in the canyon twice before, in 1996 and 2004, in an effort to mimic natural cycles on the river.