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averaging about 2,400 cfs in April, 8,300 cfs in May, and 10,000 cfs in <br />June (Table 9). Years with mean monthly flows that have provided peak <br />flows of around 40,000 cfs at State line (about 23,500 at the top of the <br />15-mile reach), which we recommend as a minimum peak to occur at a rate of <br />one in four years, average about 3,900 cfs in April, 12,900 cfs in May, <br />and 16,200 cfs in June (Table 7). Thus our spring flow recommendations for <br />the top of the 15-mile reach are summarized in Table 10. <br />The advantage of recommending a flow 'window', or range of acceptable <br />flows, rather than one set number, is that it allows flexibility in meet- <br />ing that recommendation; only in a completely regulated river could one <br />expect a set flow to be met with any certainty. The danger of recommending <br />a flow window is that it is commonly interpreted to mean that any flow <br />within the window is equally beneficial. This, however, is not the case <br />here. Based on the relationship between peak flow and abundance of squaw- <br />fish young, a flow of 30,000 cfs at the State line is not as good as a <br />flow of 38,200 cfs. Thus, the window 'sill', or low end of the range, <br />should not be interpreted as the recommendation. We therefore recommend <br />Table,10. Recommendations for spring flows (in cfs) in the 15-mile reach. <br />Mean monthly discharge <br />Frequency <br />(percent years) Peak_day April .May June <br />> 25% > 23,500 > 3,900 > 12,900 > 16,200 <br />> 25% 20,500-23,500 3,200-3,900 10,800-12,900 12,800-16,200 <br />< 50% 14,800-20,500 2,400-3,200 8,300-10,800 10,000-12,800 <br />46