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<br />\~ <br />\.\) <br /> <br />27 <br /> <br />Many of the archaeological resources along the river corridor are contained in the <br />sediment deposits that form alluvial terraces, Since the completion of Glen Canyon Dam, the <br />sediment resource has declined, The alluvial terraces where many archaeological sites are <br />located continue to erode, A system-wide method for regenerating the river terraces and <br />redistributing sediment has been identified as an essential component to maintaining future <br />integrity for cultural resources (Balsom, 1996). <br />Previous Cultural Resource [nvestili!ations: The 1996 BHBF presented an opportunity to <br />study the effects of high flow discharge from Glen Canyon Dam on alluvial terraces and margin <br />deposits along the river corridor, The flow was expected to provide system-wide mitigation to <br />most cultural sites in the Colorado River corridor through the accumulation of additional <br />sediment. The overall findings of the cultural resources studies strongly suggested that the <br />45,000 cfs BHBF flow had either no effect, no adverse effect, or a beneficial effect on cultural <br />resources, These findings support the original contention that beach habitat-building flows <br />above power plant capacity can offer a system-wide mitigation for cultural resources, Some <br />locations, especially in the Glen Canyon reach, did experience loss of sediments or re-deposition <br />of sediments in a way that, in the long run, could be detrimental to cultural resources (Balsom, <br />1996), More recent research in the physical resources area (see pages 9 through 10) indicates <br />that the timing of artificial "floods" relative to tributary inputs is the most beneficial. <br />In the past five years, the following projects have been completed: a synthesis of data <br />collected by the NPS and Tribal groups (Neal et al. 2000), mainstem flow and deposition <br />modeling (Wiele 2003), and development of a geomorphic model for predicting the <br />susceptibility of archaeological sites to erosion (Thompson and Potochnik 2000), The data <br />synthesis report (Neal et aI., 2000) identified crucial data gaps in previously collected data, <br />Wiele's (2003) stage flow and deposition modeling project provided information on estimated <br />sediment deposition at selected archaeological resource locations, given particular water releases <br />and modeled sediment loads, The geomorphic model by Thompson and Potochnik (2000) <br />attempted to distinguish erosional processes that are related to dam operations versus naturally- <br />occurring processes, Also in FY2000, a cultural resource protocol evaluation panel (PEP) was <br />organized. The panel's report (Doelle et aI., 2000) provided GCMRC and USBR with a series of <br />recommendations for program coordination and future activities, The work activities undertaken <br />since 2001 have been driven by the PEP recommendations (see below), <br /> <br />GCMRC FY2005-2006 Draft Annual Work Plan (November 10,2003) <br />