Laserfiche WebLink
<br />. J anuarv BHBF. following Sediment Inputs and Reduced Flows - is intended to <br />mobilize channel-stored fine sediment from the river bed and re-deposit them as <br />sand bars along shorelines under optimal conditions of high suspended-sediment <br />concentrations and grain sizes approximatihg natural bar textures. . H4: The <br />January BHBF does not result in sand-bar deposition that is equal to the response <br />measured in April1996 (sand bar area and volume above the 25,000 cfs stage). <br />HS: The JanuaryBHBF results in a more l'lIpid depletion of the ecosystem's fine- <br />sediment supply then was measured during the 1996 BHBF (2-3 days). H6: The <br />grain-size distribution of sand bars deposited during the January BHBF is not as <br />fine as grain-size distributions measured from sand bars deposited during the <br />1996 BHBF. <br /> <br />. <br /> <br />. Experimental (Winter) Load-Following - this element of the hydro graph is <br />mainly intended to disadvantage non-native fish recruitment in the main channel, <br />thereby achieving the most effective long~term control on predation/competition <br />through reduced population size. This reduction in population size in non-native <br />fish would result from a combination of spawning disruption and creating <br />unfavorable conditions for survival of young nori-native fish. Winter Load- <br />Following, similar to operations that occurred under "No-Action" era would <br />provide the greatest disadvantage to non-Ij.ative fish, and might be most effective <br />at reducing the non-native fish populations by causing lower recruitment over <br />several years ofimplementation. This may actually improve the quality of the <br />Lees Ferry trout fishery. Over the course of multiple years, reduction ofRBT and <br />BNT abundance is intended to result in increased HBC recruitment. H7: Winter <br />-- --. - --------ioadIotlowing does not reuuce recruitment ofRBT anc.tBNTln Grand Canyon. -.--.-- - -- - ~. <br />HS: Winter load following does not increjlse export of ecosystem sand. H9: <br />Winter load foll~wing does not produce eddy-bar morphologies that are more <br />conducive to recreational and other ecos)\stem uses. HlO: Winter load following <br />will not adversely impact food base reso$'ces. Only the lower limit of the diurnal <br />range would be constrained for purpose oflimiting detrimental impact to phyto- <br />benthos resources. Hll: HBC recruitment is not limited by RBT or BNT <br />predation. <br /> <br />. <br /> <br />. <br /> <br />Version 1.2 - 2/15/02 <br /> <br />5 <br />