The USGS held a press conference today to explain the results of a new report on the effects of the high-flow water releases from the Glen Canyon Dam.
They concluded that "High-volume water releases from Glen Canyon Dam can increase sandbar area and volume, but may also result in large increases in non-native rainbow trout downstream of the dam."
"Sandbars are built relatively quickly (hours to a few days) when new sand is available from tributaries, as occurred in 2004 and 2008, but they also tend to erode within days to several months under normal dam operations following an HFE.
"The eight-fold increase of rainbow trout that occurred in 2008 is of particular note, the report said, because rainbow trout are known predators of young humpback chub and may also compete with native fish for limited food resources."To download the accompanying 4-page Fact Sheet go to http://pubs.usgs.gov/fs/2011/3012/
Ref: Melis, T.S., ed., 2011, Effects of three high-flow experiments on the Colorado River ecosystem downstream from Glen Canyon Dam, Arizona: U.S. Geological Survey Circular 1366, 147 p.