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<br />monitored and treated with the same (or higher) level of sciell.tific-credibility and <br />sensitivity as other threatened resources in the CRE. <br /> <br />. <br /> <br />GCMRC needs to ensure that all program activities involving cultural resource <br />monitoring, research, and mitigation efforts are subject to the same level of independent <br />peer review that other GCMRC resource program activities currently undergo. <br /> <br />Through supporting this strategy, the AMP will finally have a truly credible <br />program in place for monitoring and mitigating the impacts of dam-operations on historic <br />properties of high risk, as mandated by NHP A, as well as meeting the GCP A mandate for <br />researching and monitoring the effects of sediment loss, vegetation change, experimental <br />flows, and mitigation activities on cultural resources in the CRE, as is currently being <br />done for other resources in the CRE. <br /> <br />Question: How are sediment fines routed and stored tbrougb tbe eRE under <br />differing flow regimes? <br />Question: Wbat flow regime strategies best maintain fines in tbe system and <br />enbance and maintain beacb areas? <br /> <br />NeedlRationale: The post-dam change in river regime has severely reduced fine <br />sediment input to the river (-93% reduction). Effects of this include: 1) reduced <br />turbidity, with implications for fish sUlVival; 2) decrease in bed cover by fine sediments, <br />particularly in Glen Canyon reach and above LCR; and 3) erosion of beach sands at and <br />above level of normal fluctuating flows. . <br /> <br />Approach: It is necessary to continue research and monitoring of fine sediment <br />transport and storage and develop management strategies, Sediment transport and sand <br />inventories have been a priority for research and monitoring for a number of years, The <br />system is reasonably well understood based upon: I) long-term monitoring of the <br />geographic distribution of deposits using a variety of techniques; 2) monitoring of <br />suspended sediment concentration along the mainstem and in tributaries; 3) studies of the <br />effects of experimental flows; and 4) theoretical modeling and laboratory experiments <br /> <br />An adaptive management strategy of short-durati.9:1- beach-building flows <br />following sediment input from the Paria River has been initiated but to date not <br />implemented due to lack of sufficient sediment input. Contingent beach-building flows <br />should continue to have a high priority. <br /> <br />· Study of possible long-term sediment augmentation should be conducted <br />including assessment of beneficial effects from increased turbidity and <br />increased sand supply for bed and beach rebuilding. In addition, potential <br />negative effects should be assessed, including effects at source sites, <br />pollutants, and costs relative to benefits. This might be implemented in a <br />staged fashion, with initial assessment within a two-year period and an in- <br />depth study based upon initial findings. <br /> <br />USGS SBSC GCMRC Strategic Science Plan - FY 2005-2009 <br />Draft, October 22, 2004 <br /> <br />. <br /> <br />20 <br />