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<br />large numbers and large groups of recreational users being forced to camp in increasingly <br />smaller areas.) Moreover, some specifically-valued campsite qualities such as amount <br />and spatial distribution of open sand area, boat mooring attributes, and amount of shade- <br />producing vegetation (Stewart et aI., 2000) are directly influenced by dam operations. <br />The relationship between operations of Glen Canyon Dam and camping <br />opportunities in the river corridor has been studied sporadically over the course of the last <br />three decades, using a variety of assumptions and approaches (Borden, 1976; Brian and <br />Thomas, 1984; Brown and Hahn-O'Neill, 1987; Kearsley and Warren, 1993; Kearsleyet <br />aI., 1994, 1995, 1994; Shelby et aI., 1976, 1992; Stewart et aI., 2000; Kaplinski et aI., <br />2004; see also Behan, 2000 and Kaplinski et aI., 2003 for a summary of past recreation <br />monitoring and research approaches pertaining to the Colorado River in Grand Canyon.) <br />Recent monitoring shows that sand bar camp size and opportunities have decreased <br />through time, at a rate of approximately 15% per year since 1998. Reductions in camp <br />site area and numbers are due to a combination of factors, including sediment being <br />removed from the system by dam operations, sediment being removed by tributary floods <br />(and not subsequently replaced by flood flows), and vegetation encroachment (Kaplinski <br />et aI., 2005.) <br />The lack of periodic scouring floods under current dam operations has allowed <br />vegetation to become established on many formerly open sand areas. Vegetation <br />encroachment is believed to be an important factor contributing to the reduction in size <br />and abundance of campable areas in the CRE, yet actual rates and amount of campsite <br />loss due to vegetation encroachment remain unmeasured and unknown (Kaplinski et aI., <br />2003,2005). <br />The National Park Service currently monitors approximately 100 campsites for <br />visitor use impacts such as social trailing, vegetation damage, fire scars and litter. NPS <br />recently initiated a new pilot campsite impact monitoring program to meet Park-specific <br />management needs related to the Colorado River Recreation Management planning <br />process. The current NPS recreation monitoring programs are primarily concerned with <br />tracking human impacts at campsites, rather than focusing on physical changes linked to <br />dam operations. The current NPS monitoring program will continue into the foreseeable <br />future as a separate but complementary program to the one presented here. <br /> <br />. <br /> <br />. <br /> <br />. <br />