Some Benefits From 2008 Glen Canyon Controlled Flood, But Little Sediment Reached Riverbanks

[hatrack]

Not quite two years after federal scientists blasted water from four Glen Canyon Dam release tunnels to simulate floods of pre-dam days, those experts acknowledged Tuesday only limited success in replenishing Colorado River sandbars and fish habitat. Although the 60-hour flush in 2008 took maximum advantage of the natural flooding on the Colorado tributaries, 90 percent of the sand that would replenish the river's ecology remains trapped behind the dam.

Theodore Melis, deputy chief of the U.S. Geological Survey's Grand Canyon Monitoring and Research Center in Flagstaff, Ariz., said the 2008 test adds to the evidence examined from controlled floods in 1998 and 2004. "What we saw was a direct benefit," Melis said during a telephone news conference.

The flood of March 2008 reached a peak flow of 41,000 cubic feet per second and stirred up the gravel in the riverbed, Melis said, giving rainbow trout -- a non-native species -- a better shot at survival. The timing seemed also to reduce tamarisk seedling germination. The high-flow test also pared the nuisance New Zealand mud snail population by about 80 percent, the USGS said, while midges and black flies (high-quality food items for fish) increased. It was unclear how the flood affected habitat for the native humpback chub, an endangered species that has died off as the sand dwindled below the dam, completed in 1963.

Six months after the test, the USGS reported, new sandbars had been largely eroded by fluctuating dam flow operations, driven by electrical energy demand.

EDIT

http://www.sltrib.com/news/ci_14318519

[tom_paine]

1. Who could have foreseen our attempt to replicate the actions of the natural world would be fruitless

in the long run?

:rofl: