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<br />Figure 4.3 Flow duration analyses for the Jensen gage.
<br />
<br />4.4.2 Peak Flow Frequency. Peak flow frequencies of instantaneous discharges were computed
<br />using the Geological Survey's W A TSTOR system. Peak flow frequencies for daily flows were computed
<br />using the recommended methods in bulletin 17B, "Guidelines for Determining Flood Flow Frequency".
<br />Frequency plots for all gages are presented in Appendix R Table 4.2 summarizes the results.
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<br />Table 4.2. Mean daily discharges for various return periods (cfs).
<br />Gage Return Period
<br />Location
<br /> 2 5 10 100 500
<br />Maybell 9,675 12,2fJ7 14,546 'lJ),(K)7 23,694
<br />Lily 4,384 6,339 7,625 11,572 14,252
<br />Deerlodge 13,8'lJ) 17,997 'lJ),476 27,114 30,983
<br />Jensen - Pre-dam 21,699 28,916 33,202 44,688 51,397
<br /> - Post-dam 17,466 23,569 27,188 36,808 42,353
<br />
<br />4.4.3 Representative Low. Average. and HitPt Water Years. A representative year type analysis
<br />was used to portray streamflow conditions expected within the Yampa basin during low, average and high
<br />water years. The years of record were ranked based upon the April to July flow at the Maybell gage on the
<br />Yampa River. From the 53 year period ofrecord, the 7th, 8th, and 9th ranked years were averaged and
<br />used to represent dry conditions. The 26th, 27th, and 28th ranked years were averaged to represent normal
<br />conditions, and the 46th, 47th, and 48th ranked years were averaged to represent wet conditions. The three
<br />data sets were then tested to determine if they were representative of dry, average, and wet conditions.
<br />Typically, a very wet year can have dry months, and a dry year can have a month or two of higher than
<br />
<br />4-5
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