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Manmade flood in Grand Canyon to renew ecosystem
By Amanda Lee Myers, Associated Press Writer
Thursday, March 06, 2008 | No comments posted.
PAGE, Ariz. — A manmade flood turned calm, clear water downstream from a northern Arizona dam into a frothy, choppy river. But the real story was beneath the surface.
There, scientists say water gushing from the base of the dam into the Colorado River is adding and stirring up sand that they hope will restore the Grand Canyon’s altered 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 Wednesday, the beginning of the three-day flood.
“This gives you a glimpse of what nature has been doing for millions of years, cutting through and creating this magnificent canyon,” Kempthorne said as water gushed into the river and ran along the canyon’s salmon-colored sandstone walls.
The water, which has added between 2 and 15 feet of water to the river downstream from the Glen Canyon Dam, will return to normal levels after the flood ends Friday.
As the water goes down, officials hope the sediment will stay and rebuild sandbars, which create habitat for plants and animals, provide beaches for campers and supply sand to protect archaeological resources from erosion and weathering.
Nearly all of the sediment along the Grand Canyon has been lost since the Glen Canyon Dam was built upstream in 1963. The dam, which provides water storage and hydroelectricity, also blocks sand that used to naturally build up sandbars in the Colorado river.
In 45 years, the river transformed from a warm and muddy haven for wildlife into a cool, clear environment that helped speed the extinction of four fish species and push two others near the edge.
In an effort to mimic natural cycles on the river, officials have created manmade floods in the canyon twice before, in 1996 and 2004.
Those floods actually resulted in a net reduction in overall sandbar size because they were conducted when the Colorado River was relatively sand-depleted, according to the U.S. Geological Survey. Officials believe this year’s flood will be different because sand levels in the river are at a 10-year high and are three times greater than 2004 levels.
Grand Canyon National Park Superintendent Steve Martin said any benefits from this week’s flood will be eroded away within 11⁄2 years. Manmade floods need to occur every time there’s enough sediment to do so, he said, about every one to two years depending on Arizona’s volatile monsoon season.
“The science is really clear that’s what we need to do, and if we don’t, the resources have been so diminished that we could actually impair the canyon,” Martin said.
Bureau of Reclamation Commissioner Bob Johnson said the agency wants to gather information from this week’s flood and then decide how and when to conduct future floods.
“We’re not saying we won’t do them again, we’re saying we need to get data and information to make the best decision on how that should be done,” he said. “Maybe we will do one every one to two years, depending on what the science and what the information tells us as we move forward.”
———
On the Net:
Grand Canyon National Park: http://www.nps.gov/grca.
Bureau of Reclamation: http://www.usbr.gov/
There, scientists say water gushing from the base of the dam into the Colorado River is adding and stirring up sand that they hope will restore the Grand Canyon’s altered 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 Wednesday, the beginning of the three-day flood.
“This gives you a glimpse of what nature has been doing for millions of years, cutting through and creating this magnificent canyon,” Kempthorne said as water gushed into the river and ran along the canyon’s salmon-colored sandstone walls.
The water, which has added between 2 and 15 feet of water to the river downstream from the Glen Canyon Dam, will return to normal levels after the flood ends Friday.
As the water goes down, officials hope the sediment will stay and rebuild sandbars, which create habitat for plants and animals, provide beaches for campers and supply sand to protect archaeological resources from erosion and weathering.
Nearly all of the sediment along the Grand Canyon has been lost since the Glen Canyon Dam was built upstream in 1963. The dam, which provides water storage and hydroelectricity, also blocks sand that used to naturally build up sandbars in the Colorado river.
In 45 years, the river transformed from a warm and muddy haven for wildlife into a cool, clear environment that helped speed the extinction of four fish species and push two others near the edge.
In an effort to mimic natural cycles on the river, officials have created manmade floods in the canyon twice before, in 1996 and 2004.
Those floods actually resulted in a net reduction in overall sandbar size because they were conducted when the Colorado River was relatively sand-depleted, according to the U.S. Geological Survey. Officials believe this year’s flood will be different because sand levels in the river are at a 10-year high and are three times greater than 2004 levels.
Grand Canyon National Park Superintendent Steve Martin said any benefits from this week’s flood will be eroded away within 11⁄2 years. Manmade floods need to occur every time there’s enough sediment to do so, he said, about every one to two years depending on Arizona’s volatile monsoon season.
“The science is really clear that’s what we need to do, and if we don’t, the resources have been so diminished that we could actually impair the canyon,” Martin said.
Bureau of Reclamation Commissioner Bob Johnson said the agency wants to gather information from this week’s flood and then decide how and when to conduct future floods.
“We’re not saying we won’t do them again, we’re saying we need to get data and information to make the best decision on how that should be done,” he said. “Maybe we will do one every one to two years, depending on what the science and what the information tells us as we move forward.”
———
On the Net:
Grand Canyon National Park: http://www.nps.gov/grca.
Bureau of Reclamation: http://www.usbr.gov/
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