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<br /> <br />,"l_ <br /> <br />., <br /> <br />\ <br /> <br />.. <br /> <br />Table 5.1. <br /> <br />Flo,,:", req.uirements neede~ to produce important biological responses and~~,: <br />habitats In the San Juan River. .' 0) <br /> <br /> "-'1 <br />BIOLOGICAL RESPONSE! FLOW CHARACTERISTIC , . ..~" <br />HABITAT REQUIREMENT <br /> ';':~ <br />Reproductive success of Colorado pikeminnow lower in Mimicry of a natural hydrograph, especially during <br />years with low spring runoff peaks, and higher in years relatively high runoff years, <br />with high and broad runoff peaks, <br />Decline in flannelmouth sucker abundance, increase in Mimicry of natural hydrograph with higher spring flows <br />bluehead sucker abundance, and increased condition and lower base flows, <br />factor in both species, <br />Bluehead sucker reproductive success. ....,...:.' 'Y!" " <br />~('_c.t~~~ f}_~~~er 91 d,~V~,?.f.sPJin!=l runoff >5,000 and <br /> 8 000 cfs?e:orrelaledWlthii1creased ~u~2e~, <br /> . .,--._. ~.".,,-.." .--' ". "' ,. ...... , <br />Speckled dace reproductive success. Increaslld number of days of sprinQ runoff >5,000 and <br />.-.' '-'-"^ '~~"''''''l'l'''''''~' -'p"" - .. ,- .4"~" ~ .'__E<" '7'~ <br /> 8,000 cfs~l'.ciffelated ~t~incie!.sed suqcie~~, <br />Success of stocking YOY Colorado pikeminnow and Mimicry of natural hydrograph has provided su~able <br />subadull razorback sucker, habitat for these size-classes. <br />Eddies, pools. edge pools, other low-velocity habitats Mimicry of natural hydrograph has lowered base flows <br />year round for adult Colorado pikeminnow and to provide more low-velocity habitats, Rows >10,000 <br />razorback sucker, cfs provide more channel complexity which provides for <br /> more habitat complexity, <br />Flows to cue razorback sucker and Colorado Mimicry of natural hydrograph with higher spring flows, <br />pikeminnow for migration andlor spawning, <br />Adult Colorado pikeminnow and razorback sucker ITs.; Rows> 10,000 cfs provide more channel complexity <br />complex river areas. which provides for more habitat complexity, lower base <br /> flows add to amount of low-velocity habitats, <br />Clean cobble bars for spawning of all native species, Flows >8,000 cfs for 8 days to construct cobble bars, <br />especially Colorado pikeminnow, and >2,500 cfs for 10 days to clean cobble bars, during <br /> spring runoff, <br />Backwaters and other low-velocity habitats are High spring flows create conditions for backwater <br />important nursery habitats for Colorado pikeminnow formation, low base flows allow them to appear in late <br />and other native fishes, summer and fall, flows >5,000 cfs for 3 weeks create <br /> and clean backwaters, <br />Flooded bottomlands appear to be important nursery Overbank flows (> 8,000 cfs) increase flooded <br />areas for razorback sucker, but other habitats may be vegetation. and backwaters formed in association with <br />used in the San Juan River, edge features maximize on receding flows 01 8,000 to <br /> 4,000 cfs, <br />Temperatures of 10 to 14 "C at peak runoff for Proposed releases from Navajo Dam are too cool to <br />razorback sucker spawning and near 18 to 20 "C at replicate pre-dam temperature timing, but <br />bottom of descending limb for Colorado pikeminnow temperatures are above spawning threshold for <br />spawning, Colorado pikeminnow during the correct period, <br />Reduction of nonnative fish abundance, Most nonnative fishes did not decrease during <br /> research period, summer flow spikes reduce numbers <br /> of red shiner in secondary channels in the short term, <br /> <br />.. <br /> <br />Note: cfs = cubic feet per second, YQY = young-of-the-year. <br /> <br />.. <br /> <br />SJRIP Biology Committee <br />February 1999 <br /> <br />5-4 <br /> <br />Executive Summary <br />Flow Report <br /> <br />-; <br />"~1~ <br />:1~,~ "9"4 <br />'iIl1~'.'~' <br />-~, ;,;", , <br />. ! .)jij <br /> <br /> <br />~'.:-;;,~ <br /> <br /> <br /> <br /> <br />"J <br />,",,- <br />, 1~' '" <br />"",_. <br />-~.,.~ <br />II <br />Ii <br /> <br />"4l' <br /> <br />II <br /> <br />.. <br /> <br />II <br />-~ <br /> <br />II <br />.. <br /> <br />. <br /> <br />. <br />',," <br /> <br />Ii <br /> <br />II <br />