WSP06185 - Laserfiche WebLink

Home Browse Search

~ ,. ~t :.... Pg. 211, C. 1, P. 2. The suggestion that the aquatic food base will be improved with this alternative is speculative. There is at least equal evidence supporting the opposite result (e.g., reduced growth rate, reduced sloughing, lowered nutrient loads, etc.) in areas downstream of Lee's Ferry. 1 ..,.. ,. You imply no downward adjustments in flow would occur under this alternative. This may not be correct. You should discuss the impacts to adults and redds which would occur if flows were held steady for a month and then dropped to a new, steady and lower flow. In the steady flow alternative, what would dewatering algal beds for three months do to primary production in the river? How long would it take for the production to recover from drying? Pg. 211, C. 1, P. 3. What would happen to algae grown at depth during steady flows when flows are maintained higher if algal production at depth is a function of water depth? Pg. 211, C. 1, P. 4. If the food base can' be expected to establish at some level coincident with a flow pattern, it may be incorrect to speculate that one flow pattern or another is any better or worse than any other,.' especially as it relates to growth and condition of fishes. The significance of one cap on algal colonization or any other 'should be explained if there is a reason. A fixed or slightly declining nutrient load from Lake Powell coupled with an en~arged Cladophora population near the dam may glean nutrients sufficiently to stress downstream algae. Also, with steady flows reducing the growth rate and sloughing, energy transfer downstream should decrease under this alternative. You should discuss these possibilities as to their consequences to downstream productivity rather than pass it off as of unknown significance. , ",;' ;j::j ~~ ~~~ .';:~ .-! ....,.; ,'" ~.~. . I ", .:. "I Pg. 211, C. 1, P. 5. The generalization that young native fish are limited in their ability to achieve reproductive size by cold river conditions belies the successes achieved in the LCR and other tributaries by several species of native fish. Is there evidence that the main channel in this area has ever been needed by these species to sustain their numbers? Is it not possible these species have always used tributaries in the canyon for recruitment? We have not seen data which supports the necessity for main channel spawning to sustain any native fish in the canyon. Young native fish must still travel into cold mainstem water to reach such backwaters since spawning is probably only successful in tributaries. This condition and its resulting shock may prevent survival, negating any potential benefits from backwaters. Pg. 211, C. 2, P. 3. The suggestion trout in the system will be enhanced fails to evaluate the entire system. A change in algal .~. . . _.;J l.."-j; :,';i 'c. , ~..-,i . '.~.. :;.~~ ~0 . r:'; ~';: "." 34