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River rafting trips and hikers use sandbars along the Colorado River in Marble and Grand Canyons as campsites. The U.S. Geological Survey evaluated the effects of Glen Canyon Dam operations on campsite areas on sandbars along the Colorado River in Grand Canyon National Park. Campsite area was measured annually from

River rafting trips and hikers use sandbars along the Colorado River in Marble and Grand Canyons as campsites. The U.S. Geological Survey evaluated the effects of Glen Canyon Dam operations on campsite areas on sandbars along the Colorado River in Grand Canyon National Park. Campsite area was measured annually from 1998 to 2012 at 37 study sites between Lees Ferry and Diamond Creek, Arizona. The primary purpose of this report is to present the methods and results of the project.

Campsite area surveys were conducted using total station survey methods to outline the perimeter of camping area at each study site. Campsite area is defined as any region of smooth substrate (most commonly sand) with no more than an 8 degree slope and little or no vegetation. We used this definition, but relaxed the slope criteria to include steeper areas near boat mooring locations where campers typically establish their kitchens.

The results show that campsite area decreased over the course of the study period, but at a rate that varied by elevation zone and by survey period. Time-series plots show that from 1998 to 2012, high stage-elevation (greater than the 25,000 ft3/s stage-elevation) campsite area decreased significantly, although there was no significant trend in low stage-elevation (15,000–20,000 ft3/s) campsite area. High stage-elevation campsite area increased after the 2004 and 2008 high flows, but decreased in the intervals between high flows. Although no overall trend was detected for low stage-elevation campsite areas, they did increase after high-volume dam releases equal to or greater than about 20,000 ft3/s. We conclude that dam operations have not met the management objectives of the Glen Canyon Adaptive Management program to increase the size of camping beaches in critical and non-critical reaches of the Colorado River between Glen Canyon Dam and Lake Mead.

ContributorsKaplinski, Matt (Author) / Hazel, Joe (Author) / Parnell, Rod (Author) / Hadley, Daniel R. (Author) / Grams, Paul (Author)
Created2014-07
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Description

With a focus on resources of the Colorado River ecosystem below Glen Canyon Dam, the Glen Canyon Dam Adaptive Management Program has included a variety of experimental policy tests, ranging from manipulation of water releases from the dam to removal of non-native fish within Grand Canyon National Park. None of

With a focus on resources of the Colorado River ecosystem below Glen Canyon Dam, the Glen Canyon Dam Adaptive Management Program has included a variety of experimental policy tests, ranging from manipulation of water releases from the dam to removal of non-native fish within Grand Canyon National Park. None of these field-scale experiments has yet produced unambiguous results in terms of management prescriptions. But there has been adaptive learning, mostly from unanticipated or surprising resource responses relative to predictions from ecosystem modeling. Surprise learning opportunities may often be viewed with dismay by some stakeholders who might not be clear about the purpose of science and modeling in adaptive management. However, the experimental results from the Glen Canyon Dam program actually represent scientific successes in terms of revealing new opportunities for developing better river management policies. A new long-term experimental management planning process for Glen Canyon Dam operations, started in 2011 by the U.S. Department of the Interior, provides an opportunity to refocus management objectives, identify and evaluate key uncertainties about the influence of dam releases, and refine monitoring for learning over the next several decades. Adaptive learning since 1995 is critical input to this long-term planning effort. Embracing uncertainty and surprise outcomes revealed by monitoring and ecosystem modeling will likely continue the advancement of resource objectives below the dam, and may also promote efficient learning in other complex programs.

ContributorsMelis, Theodore S. (Author) / Walters, Carl (Author) / Korman, Josh (Author)
Created2015
ContributorsWegner, Dave (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2017-08-04
ContributorsYeatts, Mike (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2018-09-08
ContributorsWegner, Dave (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2017-08-04
ContributorsWalters, Carl (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2018-08-18
ContributorsStevens, Larry (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2017-02-06
ContributorsPotochnik, Andre (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2017-12-04
ContributorsGarrett, Dave (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2018-08-09
ContributorsSchmidt, Jack (Interviewee) / Hirt, Paul (Transcriber, Interviewer, Editor) / Sweeney, Jennifer (Transcriber, Interviewer, Editor)
Created2018-06-11