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In Bishop et al. (1987; on page 410 of the 30 page report: “Grand Canyon Recreation and Glen Canyon Dam Operations: An Economic Evaluation) fluctuating flows are defined as any operation where the daily flow fluctuation was equal to or more than 10,000 cfs/day. Bishop treated daily flow fluctuations of less than 10,000 cfs/day as “constant flow releases.” Bishop identified that this “10,000 cfs threshold was determined to be the point at which fluctuations begin to be perceptible to recreationists.” Additionally and as identified on Page 4-269 line 20 of this EIS, Stewart et al.’s (2000) follow-up of the Bishop et al. (1987) study found that angler’s did not identify river level fluctuations, at least under the MLFF operating regime, as an issue. Based on information from Stewart et al (2000) and Bishop et al. (1987), any flow fluctuation below 10,000 cfs/day should be treated the same as a steady flow release.
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