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U.S. Geological Survey Fact Sheet 2011–3012

Grand Canyon Monitoring and Research Center

Three Experimental High-Flow Releases from Glen Canyon Dam, Arizona—Effects on the Downstream Colorado River Ecosystem

By Theodore S. Melis, Paul E. Grams, Theodore A. Kennedy, Barbara E. Ralston, Christopher T. Robinson, John C. Schmidt, Lara M. Schmit, Richard A. Valdez, and Scott A. Wright


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Three high-flow experiments (HFEs) were conducted by the U.S. Department of the Interior at Glen Canyon Dam, Arizona, in March 1996, November 2004, and March 2008. Also known as artificial or controlled floods, these scheduled releases of water above the dam’s powerplant capacity were designed to mimic pre-dam seasonal flooding on the Colorado River. The goal of the HFEs was to determine whether high flows could be used to benefit important downstream resources in Glen Canyon National Recreation Area and Grand Canyon National Park that have been affected by the existence and operation of Glen Canyon Dam. These downstream resources include native fish, particularly endangered humpback chub (Gila cypha), terrestrial and aquatic sandbar habitats, cultural sites, and recreational resources. This Fact Sheet summarizes HFE-related studies published since 1996 and outlines a possible strategy for implementing future HFEs.

  • This report is also available in print from:

    USGS Information Services, Box 25286,
    Federal Center, Denver, CO 80225
    telephone: 888 ASK-USGS; e-mail:

For additional information contact:
SBSC Staff, Southwest Biological Science Center
U.S. Geological Survey
2255 N. Gemini Drive
Flagstaff, AZ 86001

This report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Melis, T.S. Grams, P.E. Kennedy, T.A. Ralston, B.E. Robinson, C.T. Schmidt, J.C. Schmit, L.M. Valdez, R.A. and Wright, S.A. 2011, Three experimental high-flow releases from Glen Canyon Dam, Arizona; effects on the downstream Colorado River ecosystem: U.S. Geological Survey Fact Sheet 2011-3012, 4 p.

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