Feds Unleash Artificial Flood in Grand Canyon

Huge release from Glen Canyon Dam to refresh downstream ecosystem.

The Grand Canyon is 277 miles long and up to one mile deep, yet most of the million annual visitors to Grand Canyon National Park do not stray below the rim and never even see the Colorado River that, for 6 million years, has carved it. Right now, a dramatic artificial flood is occurring in the canyon that in addition to helping restore the ecosystem, will change the beaches where rafters camp on their multi-day river trips.

Today, federal agencies literally opened the the dam's gigantic bypass tubes on the Glen Canyon Dam of the Colorado River (for photos, click here and here). The release helps restore the ecosystem of Grand Canyon, just downstream, as 300,000 gallons of water per second pour out of Lake Powell. This periodic flood (previously unleashed in 1996 and 2004) is intended to reproduce the results natural spring floods that occurred before the dam was built in 1963.

The Colorado used to be a warm, muddy river whose natural annual floods built up sandbars that are essential to native plant and fish species. Since the construction of the dam, the river has become cooler and clearer, which is more aesthetically pleasing but not natural to the river. Since the dam was built, fish species have become extinct and and two others, including the endangered humpback chub, are nearing extinction.

During this week's three-day flood, water flows in the Grand Canyon are expected to increase to 41,000 cubic feet per second, which is four to five times the regular release from the dam. Scientists are monitoring the results of the induced flood, including habitat changes that will hopefully protect rare native species. The release from the dam is intended to mimic the natural floods that once flushed and rebuilt the narrow sand beaches along the river on the canyon floor.

The two earlier floods demonstrated the importance of sand and sediment in maintaining a semblance of the Grand Canyon's ecosysten. With the dam now trapping most of the sediment that once coursed down the river, beaches and habitats eroded, even as the Paria and Little Colorado Rivers, which join the Colorado below the dam, continue to carry sediment into the Colorado. The current flood is scouring and reshaping miles of sandy banks and beaches, and scientists and environmentalists will monitor what happens when floodgates are closed dam and flood waters recede. They have already found that the endangered chub has recovered some of its lost numbers since the last flood, and they hope that they are learning when to trigger future floods.

The feds say that they are improving the health of the Grand Canyon and are formulating long-term plans to offset the effects of the dam on the river and the Grand Canyon. "Our ultimate purpose is to learn whether or not this is a viable strategy for creating sandbars and habitats for native fish," John Hamill, chief of the Grand Canyon Monitoring and Research Center, part of the U.S. Geological Survey, was quoted as saying.

Environmental activists believe that the feds' on-and-off flooding operations delay those long- term policy changes and thereby jeopardizing the canyon's health. Environmentalist want the dam's operation to be altered permanently to better mimic nature's cycle rather than instead of repeating the same artificial flooding every few years.

I have been down to the river twice, once step-by-step on a four-day backpacking trip and once one paddle stroke at a time on river trip. Both were in late September. We backpacked from the South Rim descending on the South Kaibab Trail, crossed the river at Phantom Ranch, climbed up the North Rim, came back down, crossed the river gain and hiked up to the South Rim on the Bright Angel Trail. Some years later, we did a river trip on the Lower Canyon that began with a 7 1/2-mile hike down Bright Angel Trail to meet our raft outfitter at Pipe Creek (river mile 89) and rafted to (mile 225). I'm grateful to have not just looked down into the canyon from the rim or flown over it in a helicopter but experienced it up close and personal, to me always the best way to travel.