The Department of the Interior's Bureau of Reclamation has just released for public comment a draft Environmental Assessment that describes a proposed late-November high-flow test experiment through the Grand Canyon from Glen Canyon Dam.
"Interior continues to support the application of science and adaptive management to the operation of Glen Canyon Dam and the management of natural resources in Glen and Grand Canyon," Interior Secretary Gale Norton said in announcing the Environmental Assessment. "Experiments such as this high-flow test continue to advance our understanding of the ecosystem while providing tangible benefits to the fishery, river environment, and recreational users in Grand Canyon National Park."
In August 2004, members of the Glen Canyon Adaptive Management Work Group recommended to Norton 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.
In October, the Grand Canyon area experienced significant rainstorms that produced Paria River sediments that are 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 determined 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 will be available for public review on the Internet by following the link at www.usbr.gov/uc/envprog/amp, or by contacting Dennis Kubly, Bureau of Reclamation, Upper Colorado Regional Office, 125 S. State Street, Salt Lake City, Utah 84138, and by telephone at (801) 524-3715.