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Glen Canyon planning flow experiment<br>

In accordance with the National Environmental Policy Act, the right sediment conditions in the river had to be present to trigger the recommendation for an experimental high flow.

If the EA is approved, Reclamation will open the dam’s bypass tubes for 90 hours beginning Sunday. The peak high flows would occur for 60 hours from 4 a.m. on Monday until 4 p.m. next Wednesday, at a rate of about 41,000 cubic feet per second.

According to park Management Assistant Leah McGinnis, in contrast, the river’s normal flow is between 5,000 and 10,000 cfs.

If the release is approved, boaters are advised to secure all vessels when camped along the river and campers are warned to set up outside the range of the flows.

Last August, members of the Glen Canyon Adaptive Management Work Group recommended that high-flow tests be considered for later in the year if sufficient accumulations of sediment were present in the Colorado River near the confluence of the Paria River. October’s significant rainstorms produced Paria River sediments sufficient to trigger such a test.

The primary purposes for conducting the high-flow tests are to restore sandbar deposits in the upper reaches of the Grand Canyon and recreate numerous backwater channels that serve as prime spawning areas and habitat for the humpback chub and other native fish species.

Researchers have determine that the future of Grand Canyon sandbars requires careful management of sediments coming from tributaries, daily water release patterns, and the frequency and magnitude of flood releases from the dam over the long-term.

Researchers believe that the high-flow tests will restore a dynamic flow component to the river and provide some of the processes of a natural system.

The Environmental Assessment is available for public review on the Internet by following the link at www.usbr.gov/uc/envprog/amp, or by calling Dennis Kubly at the Bureau of Reclamation’s Upper Colorado Regional Office, at 801-524-3715.


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