WHEN Interior Secretary Bruce Babbitt opened a valve at Glen Canyon Dam in Arizona this week, he didn't just send billions of gallons of water surging down the Colorado River. He also opened up what could be a new and more benign way of manipulating the power and promise of rivers, whose artificial plumbing has brought economic vitality to the arid American West.
By creating a deluge that will pattern the annual spring floods that occurred when the river ran free, officials hope to restore beaches and wildlife habitat along the Colorado that have been degraded over since Glen Canyon Dam was dedicated by Lady Bird Johnson in 1966.
Instead of simply blocking the water's flow and then releasing it every day or so to meet peak power and water needs, this experiment aims to mimic nature and in the process protect important natural, archaeological, and recreational interests.
"It's a new era for ecosystems, a new era for dam management, not only for the Colorado but for every river system and every watershed in the United States," Mr. Babbitt told a crush of reporters and officials gathered at the dam Tuesday.
What's also unique here is that typically diverse interests - conservationists, Indian tribes, and those who generate and market electrical power - have been willing partners in exploring new scientific and political ground.
"What we're doing is putting back a really vital process for the river ... a very significant part of what naturally kept the river in balance," says Pam Hyde, regional director of the environmental group, American Rivers.
Leigh Jenkins, director of the Hopi tribe's cultural preservation office in Kykotsmovi, Ariz., says rebuilding beaches will protect more than 300 Hopi pueblo and archaeological sites that have suffered adverse effects (including the unearthing of sacred burial grounds) due to erosion caused by prior river management.
Electric utilities that rely on the dam for the power they sell throughout the Southwest warn that one result of the new water management could be an increase in costs - either charged directly to customers or passed on to taxpayers. Every kilowatt-hour of energy "lost" downriver, they say, must be bought elsewhere.
But utilities also are willing to abide by what the ecologists, hydrologists, and other specialists report once the experiment is completed, says Joe Hunter, executive director of the Colorado River Electrical Distributors Association.
The Glen Canyon Dam was built before several important environmental laws were passed, including the National Environmental Policy Act (1969), the Endangered Species Act (1973), and the Grand Canyon Protection Act (1992). So no environmental impact statement outlining possible consequences was required at the time.
Over the years, the dam (which created Lake Powell) trapped much of the sediment that normally would have regenerated beaches downstream, maintained the river's normally warmer temperature, and enriched the habitat for native plants and fish.
As a result, several fish species have dwindled toward extinction, and exotic species such as rainbow trout and cottonwood trees have thrived. The Hopi and Hualapai tribes, the Navajo Nation, and the Zuni Pueblo also have reported damage to important cultural sites along the river as the beaches eroded.
In response to growing concerns, former President Bush's Interior Secretary Manuel Lujan ordered an environmental impact statement, which was issued in draft form last year. The statement (under review by the federal General Accounting Office) recommends changes like the flooding of the Grand Canyon.
These include providing for more moderate adjustments to river flow rather than large fluctuations to meet daily peak power demands. Also anticipated are annual "beach/habitat maintenance flows" and, every five to 10 years, a high-volume flow of the type being conducted this week.
The test began last Friday, when water flow was held to 8,000 cubic feet per second to establish baseline data. On Monday night, the water flow was gradually increased to 45,000 cubic feet per second where it will remain for one week. Then the flow rate will be gradually reduced to the 8,000 cubic-feet-per-second level.
The man-made flood is expected to total nearly 120 billion gallons of water and raise the river level by 10 to 15 feet inside the Grand Canyon. It will spend itself when it reaches Lake Mead and Hoover Dam nearly 300 miles downstream.
ACCORDING to Interior Department officials, the test is designed to rebuild higher-elevation sandbars by stirring sand deposits up from the river channel, restore backwater channels, prevent channels from becoming overgrown with vegetation, and restore the river's natural dynamics.
"After so many years of concentrating on water capture and power generation, this test is a symbol of our new commitment to making environmental restoration an equal part of the water equation of the West," Babbitt said.
The experiment has also been successful in including more parties from the start to determine new directions in resource management policy.
"It's been a great model for including a lot of stakeholders - whether their interests are monetary or philosophical - sitting down with river managers and making those decisions," says Ms. Hyde of American Rivers.