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U.S. Geological Survey Circular 1366

Grand Canyon Monitoring and Research Center

Effects of Three High-Flow Experiments on the Colorado River Ecosystem Downstream from Glen Canyon Dam, Arizona

Edited by Theodore S. Melis


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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. These experiments, also known as artificial or controlled floods, were large-volume, scheduled releases of water from Glen Canyon Dam that were designed to mimic some aspects of pre-dam Colorado River seasonal flooding. The goal of these experiments was to determine whether high flows could be used to benefit important physical and biological resources in Glen Canyon National Recreation Area and Grand Canyon National Park that had been affected by the operation of Glen Canyon Dam. Efforts such as HFEs that seek to maintain and restore downstream resources are undertaken by the U.S. Department of the Interior under the auspices of the Grand Canyon Protection Act of 1992 (GCPA; title XVIII, secs. 1801–1809, of Public Law 102-575). Scientists conducted a wide range of monitoring and research activities before, during, and after the experiments. Initially, research efforts focused on whether HFEs could be used to rebuild and maintain Grand Canyon sandbars, which provide camping beaches for hikers and whitewater rafters, create habitats potentially used by native fish and other wildlife, and are the source of windborne sand that may help to protect some archaeological resources from weathering and erosion. As scientists gained a better understanding of how HFEs affect the physical environment, research efforts expanded to include additional investigations about the effects of HFEs on biological resources, such as native fishes, nonnative sports fishes, riverside vegetation, and the aquatic food web. The chapters that follow summarize and synthesize for decisionmakers and the public what has been learned about HFEs to provide a framework for implementing similar future experiments.

This report is a product of the Glen Canyon Dam Adaptive Management Program (GCDAMP), a Federal initiative authorized to ensure that the primary mandate of the GCPA (GCPA sec. 1802 (a)) is met through advances in information and resource management. The program and its research efforts focus on a study area that encompasses the Colorado River corridor from the forebay of Glen Canyon Dam to the western boundary of Grand Canyon National Park, which is identified as the Colorado River ecosystem elsewhere in this report. The study area includes the approximately 16-mile river corridor between the dam and Lees Ferry within Glen Canyon National Recreation Area and the entire 277-river mile corridor downstream from Lees Ferry and within Grand Canyon National Park. The U.S. Geological Survey’s Grand Canyon Monitoring and Research Center (GCMRC) is responsible for the scientific monitoring and research efforts of the GCDAMP, including the preparation of this report. The GCMRC gratefully acknowledges the contributions of those scientists with Federal and State resource-management agencies, academic institutions, and private consulting firms who undertook much of the research presented in the chapters that follow.

  • Report PDF (standard resolution; 8.6 MB)
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  • This report is available only on the Web at this time; a press run is planned.

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., ed., 2011, Effects of three high-flow experiments on the Colorado River ecosystem downstream from Glen Canyon Dam, Arizona: U.S. Geological Survey Circular 1366, 147 p.


Chapter 1. Introduction and Overview

Chapter 2. Understanding Physical Processes of the Colorado River

Chapter 3. The High Flows—Physical Science Results

Chapter 4. Biological Responses to High-Flow Experiments at Glen Canyon Dam

Chapter 5. Science-Based Strategies for Future High-FlowExperiments at Glen Canyon Dam

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