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<br />~~_B <br /> <br />- "~C1 C!?:...J~ 'J~:,::-, <br /> <br />F'.3 <br /> <br />quali~y wo~ld be th=ouS~o~~ t~e year, s~=~ld a variable <br />intake be used. Nt.:-:~ient c.vnamic and ":e~oera~:lre ~oc.els <br />need ~o be developed for ~he river fro~ :~e dam down to at <br />least Grand canyon, tha~ is, past ~he pr~~ary ~rout and <br />~umpbac~ chub fishery areas. Nutrien~-pr~duc:~vi~y <br />relationships need ~o be re:ined. ?red~c~ions of downstream <br />changes might then be ~=de if quality of discharge water is <br />tied to the variable levels in the Lake ?cwell profiles (see <br />H.-7.1). <br /> <br />C. Effects of a Rerecrulat:on Da~ <br /> <br />IS. Question: If a reregulation dam were constructed in ~~e <br />Canyon some where between Glen Canyon Dam and Lee's Ferry, what <br />would be the effects of the discharges, and variations in both <br />water quantity and quality, on ~he downstream ecosystem? What <br />also would be the effects on the system in ~~e location of the <br />impoundment behind the reregulation dam? <br /> <br />H.-1S.1. There will be no significant differences between <br />the response of the downstream canyon ecosystem to discharges <br />from a reregulation dam and ~he discharges from Glen Canyon Dam. <br /> <br />Justification: The purpose for cons~ruc~ing a reregulation <br />dam is to create a more natural downstream flow, in both <br />quantity and quality. How possible it would be to create <br />such a natural discharge and how different that discharge <br />would be from the ey.ist~ng discharges need to be known. <br /> <br />Information Needs: A hypothetical model will need to be <br />developed to test various parameters of the dam, water <br />discharge system and impoundment to dete~ine how these will <br />affect the water quality and quanti~y d~scharged down <br />stream. Information on quality and quantity of input from <br />discharges below Glen Canyon Dam will need to be ~~own (~- <br />13.1 will answer some of this). <br /> <br />~-lS.2. The will be no significant ~mpact on the Lee's <br />Ferry reach of the Canyon if a reregulation dam is const=ucted in <br />the reach. <br /> <br />Justification: <br />inundate a yet to be <br />The magnitude of ~he <br />determined. <br /> <br />Construction of a reregularion =am will <br />determi~ed length of the Lee's Ferry reach. <br />effects of ~his inundation needs to be <br /> <br />Information Needs: Once the length of the Lee's Ferry reach <br />that will be inundated is determined, basic biological, physical <br />and ecological infornation can be used to determine pctantial <br />impacts. This basic informa~ion has been ga~~ered, in part, in <br /> <br />19 <br />