PAGE, Ariz. — For 40 years, Glen Canyon Dam has stood as a brawny symbol of growth in the Southwest, taming the flow of the Colorado River and supplying electricity to booming communities.
But the dam is putting an environmental stranglehold on a national symbol just downstream: the Grand Canyon.
Like a giant concrete stopper, the dam has plugged the seasonal ebb and flow of sediment and water temperature. As a result, four native fish are gone and a fifth — the humpback chub — is disappearing and might not have enough adult fish left to sustain the species. Gone, too, are most of the wide, sandy beaches used by whitewater boaters as camping spots.
"The canyon is in worse shape now than it was 10 years ago," said Geoffrey Barnard, president of the Grand Canyon Trust.
In 1992, faced with evidence of deteriorating conditions along the Colorado River, Congress passed the Grand Canyon Protection Act, giving the Department of Interior secretary the power to protect and restore the landmark.
Four years later, Secretary Bruce Babbitt used that authority to open the dam floodgates and force sand down the canyon to restore the beaches and the areas used as refuge by the chub.
Canyon experts acknowledge that rather than pull sand up from the Colorado River bottom, all the churning water did was move sand from one beach to another. But from that failure has come another, more ambitious plan to flush the canyon in January.
If Secretary Gale Norton approves the proposal sent to her in April, engineers will open the floodgates for two days. Instead of simply redistributing sand in the Colorado, creating a "rob Peter to pay Paul" situation, scientists hope to draw on sediment from the Paria River, a tributary 15 miles below the dam.
The Bureau of Reclamation, which has authority over the dam, is holding two public hearings next week as it prepares an environmental assessment of the January project.
"It's a big roll of the dice," Barnard said. "We're not saying we have the answer, we're just saying we have to try harder."
But groups such as the Sierra Club and Living Rivers believe efforts to mimic nature are doomed to fail and that nothing short of removing the dam will save the river.
Their prophet is the late environmental writer Edward Abbey, who in 1975 wrote "The Monkey Wrench Gang," about four eco-saboteurs' dream of blowing up Glen Canyon Dam.
Overshadowed by the magnificent Grand Canyon nearby, Glen Canyon was viewed by Congress as expendable during the approval of public-works projects in the mid-1950s.
Many conservationists and environmental groups fought the dam's construction, saying the loss of Glen Canyon was not worth the irrigation benefits and electricity the dam would produce.
They cited explorer John Wesley Powell, the first white man to visit the canyon, in their futile attempt to halt the project. In his journal, Powell marveled at "a curious ensemble of wonderful features ... carved walls, royal arches, glens, alcoves, gulches, mounds and monuments."
It took 10 years to build the 710-foot-tall dam and 17 years to create 186-mile-long Lake Powell behind it. The features Powell noted disappeared under 560 feet of water.
In 1996, the Sierra Club board of directors voted in favor of a proposal to drain Lake Powell. Last spring, the organization ran television ads in Arizona urging the canyon's restoration.
That prompted a backlash from pro-dam groups led by Republican Reps. John Shadegg of Arizona, James Hansen and Chris Cannon of Utah and Jim Gibbons of Nevada, who have denounced "radical environmentalists."
Residents of the town of Page, who love the $400 million in tourist revenue the vast lake generates, have erected billboards that shout: "Don't Let the Sierra Club Drain Lake Powell."
The number of people who remember what Glen Canyon was like a half-century ago is dwindling. Most live in Page, a town built to house the workers who built the dam. Their memories and notes paint a vastly different picture of what exists today.
Before the dam, spring runoff made the Colorado River so murky that only hardy fish such as carp, catfish and humpback chub lived there. Even in June, the river still carried enough sediment each day to fill the Rose Bowl to the rim, according to a study in 2000 by an Interior Department lawyer.
Pre-dam water temperatures varied, reaching 80 degrees in the summer and dropping to near-freezing in the winter.
But with the dam acting as a silt strainer, the released waters are as clear as gin and the year-round temperature never varies much from 46 degrees.
The clarity and temperature are a bane to native fish, but a perfect habitat for voracious brown and rainbow trout, which were introduced by Arizona game wardens.
The habitat has proved so friendly that scientists estimate there are 325,000 trout squeezed into the 15 miles of Colorado River between the dam and where the Paria River enters. Those fish feed on the chub and push them out of their native waters.
Before his present job as superintendent of Grand Canyon National Park, Joe Alston was superintendent at Glen Canyon National Recreation Area, which attracts 2.5 million tourists annually. He also is a member of the panel that recommended the January flooding.
He defends the 1992 effort as an experiment with good intentions.
"People thought flooding might be a panacea. As long as you did that every once in a while you'd have your beaches and the chub would have a place to spawn. It was a reasonable thing to think, given what we knew," he said.
The flood provided information about sediment flows that they couldn't have gotten otherwise.
Now, scientists want to reduce the flow through the end of the year to retain sediment from the Paria and another tributary in the Colorado's main stem. That repository of silt would be carried downstream by January's flushing to replenish the sand bars and create eddies where the chub can hide.
The experts are counting on the massive influx of sediment to disrupt trout spawning. They also hope to shock the river with electricity so that stunned trout float to the surface and can be removed.
"Our target is to reduce the trout population to 100,000 in the first 15 miles," said Randy Peterson of the Bureau of Reclamation.
The group that put the plan together is optimistic that it will work and that they'll be allowed to have additional water releases when needed.
But Alston urges caution. "A staggering amount of science went into the proposal. If it works, a lot of people will be happy with this. But I'm somewhat discouraged because I'm not sure if we can reverse the effects of the dam."