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About the Author: A native of Ohio, Larry Stevens received his undergraduate degree from Prescott College and his MS and PhD from Northern Arizona University in Flagstaff, Arizona. He is an avid natural historian and river runner, and has spent the past quarter century engaged in research on river ecology, with an emphasis on riparian zones. He studies dam impacts, native and non-native vegetation dynamics, biogeography, and ecological processes in river ecosystems, particularly the Colorado River ecosystem in the Grand Canyon. He has worked for various Department of the Interior agencies, and is presently a consulting ecologist in Flagstaff.
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| .INTRODUCTION |
Grand Canyon is one of the most revered natural landscapes in the world, and the condition of the Colorado River ecosystem within it is a widely discussed and debated issue (Schmidt et al. 1998). The Colorado River in Grand Canyon is strongly affected by Glen Canyon Dam, 15 miles upstream from Lees Ferry at the upriver end of Grand Canyon. This dam-regulated ecosystem is managed for, or affected by, many different societal values, including the seemingly contrary goals of preservation and exploitation. Here, we will take a look at the current condition of this great ecosystem in relation to its history and discuss how current conditions may result in future changes.
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| .BACKGROUND INFORMATION |
The Colorado River in Grand Canyon has become one of the most thoroughly studied large regulated river ecosystems in the world. An enormous amount of information is available on pre-dam and post-dam conditions in Grand Canyon, including information on geology, geomorphology, hydrology, water quality, biology, and cultural resources. Pre-dam biological information is available from diaries, oblique and aerial photography, a few published studies (e.g., Clover and Jotter 1944), and surviving pre-dam residents and river runners (Webb 1996, Stevens et al. 1997a). The National Research Council (1991) and Carothers and Brown (1991) summarized what was known about dam impacts prior to 1990, and Webb et al. (1999b) and a soon to be released Invited Feature in Ecological Applications provide the results of numerous studies of the 1996 experimental flood period. The knowledge gained here is contributing to improved river and dam management, not only in Grand Canyon, but throughout the world.
Take a look at the Grand Canyon Monitoring and Research Center State of the Colorado River Ecosystem website at (http://www. gcmrc.gov). This site contains updated information on the condition of all resources in the Colorado River corridor, and is a primary source of information on existing conditions. Much of the following information on individual resources has been extracted from this report. For a listing of available literature on the entire Grand Canyon, see Earle Spamer’s Bibliography of Grand Canyon, available from the Grand Canyon Association, Grand Canyon, Arizona.
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The largest recent changes in the Colorado River in Grand Canyon have been in the realm of river management. Over the past several years, management of the river has changed from a "behind closed doors" approach to an open, adaptive strategy involving all the major environmental and economic stakeholders. Of course, this transformation has a lengthy history and one full of conflict. Following his river explorations in 1869-1871 and during his directorship of the U.S. Geological Survey, John Wesley Powell recognized the need for regional water resources development in the West (Stegner 1954, Rabbit 1975). Potential conflicts between resource exploitation and conservation were recognized in the authorizing legislation for Grand Canyon National Park (1919-1925); however, legislation authorizing water resource exploitation predominated over river-affected resource conservation until the passage of the National Environmental Policy Act (1973), the Endangered Species Act (1973), and the Grand Canyon Protection Act (1992). The U.S. Fish and Wildlife Service issued a 1978 Jeopardy Opinion on the operation of Glen Canyon Dam because of its apparent impact on endangered native fish. These conflicts eventually resulted in the production of one of the nation’s largest Environmental Impact Statements in 1995.
In 1996 the Secretary of the Interior supported the recommendations
of that EIS by issuing a Record of Decision on the operation
of Glen Canyon Dam. The ROD authorized an adaptive management
approach, sediment-conserving flows, and a long-term scientific
monitoring program to improve river management. This ROD
created an Adaptive Management Work Group (AMWG), a Federal
Advisory Committee that includes representatives of 27 major
stakeholder groups, including the Western Area Power Administration,
several Department of the Interior agencies (Bureau of Indian
Affairs, Bureau of Reclamation, Fish and Wildlife Service,
National Park Service), the Colorado River basin states,
the Arizona Game and Fish Department, seven Native American
tribes, and representatives of power marketing, recreational
and environmental advocacy groups. The AMWG meets semiannually
to develop recommendations on how to manage Glen Canyon
Dam to the Secretary of the Interior. Dam releases are constrained
to 5,000 to 25,000 cubic feet per second (cfs). Scientific
monitoring and research activities are coordinated by the
U.S. Geological Survey’s Grand Canyon Monitoring and
Research Center (GCMRC) office in Flagstaff, Arizona, and
the AMWG is advised by a subcommittee, the Technical Work
Group (TWG), which works closely with GCMRC. As a Federal
Advisory Committee, all AMWG and TWG meetings are advertised
and now open to the public.
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