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<br />Habitat maintenance flows are defined as high, steady releases within powerplant capacity <br />(33,200 cfs maximum) for 7 to 14 days in March or April. Other momhs could be considered <br />under the Adaptive Management Program. Habitat maimenance flows would occur every year <br />in which. lake Powell is not expected to spill and would not occur when beach and habitat <br />building flows are scheduled. Beach and habitat building flows would be of greater magnitude <br />(40;000 t045,000 cfs) and occur .less frequently, 1 inS years when Lake Powell is low (60% - <br />of time), for an occurrence in all years of 1 "in 8 years or 12 % (Tim Randle, personal <br />communication). Neither maintenance nor building flows would occur in a year when there is <br />special concern for a,'sensitive resource, for example, a good year class of humpback chub in <br />the upper reaches of. the mainstem. The Adaptive Management Program would coordinate such <br />recommendations. <br /> <br />Figure 2 shows a plot of monthly releases for the proposed action during a minmum release <br />year. The habitat maintenance flow is included in March, but could occur in April. <br /> <br />Modified Low Fluctuating ~iow Alternative <br /> <br />Minimum Relea~e rear (= ~J maf) <br /> <br />4' <br /> <br />40 <br /> <br />" <br /> <br />~ '0 <br />:': IU. ..'".......,. ~'o.. <br />v (,,,y.......,\I.,,,..tc"._l <br />0 <br />0 '5 <br />~ <br />~ <br />. 20 <br />. <br />. <br />. <br />~ 15 <br />.! <br /> '0 <br /> 5 <br /> 0 <br /> <br /> <br />OCT NaV DEe ..JAN f:Ea tJ.AR AP;;J MAY JUN JUL AU:; SEP <br /> <br />Wate" Year <br /> <br />~ <br /> <br />Figure 2. Monthly releases of preferred alternative with minimum (solid), <br />mean (single line), and range (arrows and stiple)(Craig Phillips, <br />Reclamation, Written Communication). <br /> <br />The MLFF also includes the following elements: <br /> <br />o Flood protection limiting the frequency of floods greater than 45,000 cfs to no more than <br />I in 100 years. <br />o An Adaptive'Management Program including long-term monitoring and research. <br />o Further study of a ,Selective Withdrawal Structure (multi-level intake structure). <br />o Beach and habitat building flows - a controlled flood between 40,000 and 45,000 cfs <br />(may be greater, still being defined). <br /> <br />Further description of the alternative is found in the Draft EIS. <br /> <br />15 December 1994 fmal biological opinion 2-21-93-F-167 <br /> <br />6 <br />