Laserfiche WebLink
<br />. <br />. , n.on,~'~ <br /> <br />.. <br /> <br />water in streams. Flows in the Blue River below Dillon Dam have been <br />dropped to the 9-l8 cfs range every year from 1976 through 1985! These <br />reductions have almost invariably occurred from October through April during <br />the critical winter period when all life stages of the brown trout are <br />largely (if not totally) immobile in the gravel and very susceptible to <br />freezing during dewatering operations. <br /> <br />Cachela Poudre River <br /> <br />Minimum flow recommendations for brown trout in the Cache la Poudre <br />River are 50 cfs for all life stages, while optimum flows for juvenile and <br />adult brown trout is lOO cfs. Spawning, incubation, and hatching minimum <br />flow recommendations for rainbow trout .are lOO cfs, while fry and juvenile <br />rainbow minimum flows are 50 cfs. The adult rainbow minimum flow needed is <br />100 cfs, with an optimum of 150 cfs. While the minimum flow recommendations <br />for ,rainbows are double those of browns for many life stages (see Table 3), <br />they are flows that are almost always in the river for the spring-summer <br />spawning, incubation, and hatching life stages under any sort of <br />hydrologig~l regime. The year-round adult rainbow minimum flow <br />recommendation of 100 cfs is a flow level that is not currently met during <br />the winter months in any year. <br /> <br />Colorado River <br /> <br />Minimum flow recommendations for brown trout in the Colorado River for <br />all life stages are l25 cfs, while optimum flows vary from l25 to 250 cfs, <br />depending upon life stage. Minimum flows for rainbow spawning, incubation, <br />and hatching are l75 cfs, while minimum flows for fry, juvenile, and adult <br />rainbows are l25 cfs. Optimum flows for rainbow trout (depending upon life <br />stage) range from 125 to 300 cfs (Table 3). <br /> <br />Examination of .the flow records for the Colorado River at Hot Sulphur <br />Springs reveal that most of the minimum flows and, in many instances, the <br />optimum flows for rainbow trout are met most of the time in the majority of <br />. calendar years. The adult rainbow trout optimum flow of 200, cfs is the only <br />life stage that is significantly violated in the late summer to early spring <br />(September-March) period in most years. <br /> <br />In contrast to the rainbows, minimum flows for brown trout spawning, <br />incubation, and hatching are almost never met. Using thel25 cfs minimum <br />flow recommendation and applying it as .the standard, the records show that <br />there were only 12 months out of l54 possible for the September-March period <br />from October 1964 through September 1986 when the mean monthly flow for <br />brown trout was reached only 7.8% of the time for the September-March <br />period. Eight of those l2 months have come in the 1983-85 period, the <br />direct result of the incredibly high water years inl983 and 1984. <br /> <br />Table 4 shows the comparison between the mean monthly discharge from <br />1905 through 1945 (essentially pre-Granby Reservoir-Big Thompson Project) <br />and 1964-l985 (the current operational scenario for the Colorado River at <br />Hot Sulphur Springs. It should be. noted, however, that the additional drain <br />put on the Colorado River (at Hot Sulphur Springs) by the Windy Gap Dam and <br />Diversion Project, as of 1985, is not reflected in the data. Given these <br />statistics, it is obvious that the Colorado River should not be dewatered <br />further. <br /> <br />B 00002390 <br />