That’s the assessment of a U.S. Geological Survey report that studied the results of a 2008 experiment. A controlled flood let more water through Glen Canyon Dam in order to replicate the effects of annual flooding from before the dam was built. Sediment from the flood increased the size of sandbars along the path of the river. These sandbars are an essential habitat for the plants and animals living in the canyon and also make handy beaches for weary hikers who have just made it to the bottom.
Unfortunately, the sandbars all but washed away after six months. The USGS and Interior Secretary Ken Salazar are calling for regular controlled floods, especially in spring when the tributaries of the Colorado River naturally flood, and March in order to stop seeds from the nonnative tamarisk from germinating and helping native trout as they grow to maturity. The Glen Canyon Dam was built in the 1960s amid a major controversy over how it would change the river. Several local species have drastically reduced in number because of changes to water temperature and flow.
The problem is, the dam on the Colorado River is a major source of hydroelectric power, and any flooding would reduce the amount of electricity generated. It’s a classic case of industry vs. environmentalism, but the huge amount of money generated from tourism to the Grand Canyon may mean the environmentalists have the money on their side for a change.