WSP06185 - Laserfiche WebLink

Home Browse Search

----- ~ t r , Do daily fluctuating releases from Glen Canyon Dam also influence expansion of vegetation from the NHWZ to sites at higher elevations? 2) Does the process documented within the OHWZ by the EIS, that is replacement of long-lived, mesic-adapted species like mesquite by long-lived, xeric-adapted species like barrel cactus, seem likely to occur if the upper elevations of the NHWZ are affected by a changing water regime? Please provide sufficient detail for the reader regarding these elements. Equating 500 cfs changes in stage with a 0.2 foot change in surface elevation of the river is insufficient. Finally, as this is largely an impact related to the alternatives, it seems most appropriate that this discussion be added to Chapter 4 in adequate detail. Pg. 117, C. 2, P. 2. Are there studies of vegetation in the NHWZ by which to compare fluctuating flow versus maximum flow impacts on vegetation establishment? l .~~ .' :.1 Pg. 117, C. 2, P. 3. preceding paragraph composition. The same comments and questions raised in the are relevant with respect to species f..... .- ~~ .< ..'. .<, Pg. 118, C. 1, P. 1. The importance of geologic strata is also relevant in how vegetation is distributed. Quite simply, softer strata (i.e., Bright Angel shale) provide more opportunities for development of extensive riparian habitats than harder strata (Le., schist). ,,' Pg. 118, C. 2, P. 2. How does the productivity in Grand Canyon compare with marsh productivity elsewhere on the Colorado River ? Are there studies of lower Colorado River marsh production which could be used for comparison with Grand Canyon marshes? How can your data help differentiate between effects of fluctuating flows and 1983-86 floods in context of marsh studies ? " I .:' ;0:,." Pg. 118, C. 2, P. 3. How were fluctuating flow effects addressed in marsh studies? Does this design get at the question of how fluctuating flows affect marsh productivity? If not, how can the studies help us reach a conclusion regarding the effect of fluctuating flows on marsh productivity? were there "controls" used in any studies for comparison without fluctuating flows? If so, how were they designed? Pg. 125, C. 1, P. 1. This paragraph describes the "Grand Canyon" population of chub. You should also describe the Little Colorado River population of chub which remains year-round in the LCR. :.-.- "{. i.. ;J ... ;~~~ ... " ,... You should speculate on the reasons for the tremendous differences in gear efficiencies and what this may mean regarding habitat preferences and estimates of populations. Pg. 126, C. 1, P. 1. You speculate regarding size as the determining factor in the chub being able to withstand the cold 27