Agencies propose flooding Grand Canyon to improve critical habitat

Interior Department agencies want to release a high volume of water from Glen Canyon Dam in Page, Ariz., into the Colorado River in early March in hopes that higher water flows will move sand out of the riverbed and restore sandbars throughout Grand Canyon National Park.

Sandbars throughout the 277-mile length of the park provide critical habitat for wildlife and protect archeological resources. High water flows also create backwaters needed by native fish, including the endangered humpback chub. Since the dam began blocking water in the early 1960s, a number of native fish species have died off and non-native plants have taken root, significantly disrupting the canyon's delicate ecosystem.

The proposal, which would involve scientists and engineers from the U.S. Geological Survey, National Park Service, Fish and Wildlife Service, and Bureau of Reclamation, was announced this week and stems from previous high-flow experiments conducted in 1996 and 2004.

Sand levels in the riverbed are at a 10-year high, more than three times the volume available in 2004, creating a unique opportunity to rebuild the sandbars, said John Hamill, chief of the U.S. Geological Survey's Grand Canyon Monitoring and Research Center: "Given the current amount of sand in the system, we have a tremendous opportunity to learn more about whether high flows can be used to improve important natural, cultural and recreational resources in Glen and Grand Canyons."

If the experiment is approved, the Bureau of Reclamation would release water from the dam and its power plant up to a rate of 41,000 cubic feet per second for about 60 hours, significantly higher than previous release rates between 8,000 and 20,000 cubic feet per second. The increased flow will change river conditions as well as the availability of campsites, something Interior officials are asking river users to prepare for.

Overall, water released into the river would not change for 2008, because agency officials will reduce future releases throughout the year by levels equivalent to the water released in the experiment. Current plans call for a total 2008 release of 8.23 million acre-feet of water from Glen Canyon Dam into the Colorado River.

The bureau is conducting an environmental assessment, which is to be completed by early February. Interior officials expect to make a final decision on the proposal by the end of the month. If the plan is approved, flows could begin increasing as early as March 4.