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<br />While storms of this type have not as yet produced major floods in the
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<br />Yarnpa River there is no reason to suppose that ~hey could not in ~he
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<br />future. As one indication, Technical Paper No. 38 indicates that this
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<br />region's 24 hour PHP is very 'similar to that of the San Juan Hountains
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<br />and the Gr'and Nesa area.
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<br />E~amination of 'pre~ipitation records indicate that the ,tropical type
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<br />stonn of October 1925 produced 1.13 inches of rain at Steamboat Sprin!ls
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<br />over' a two day period. A similar storm in September 1939 produced 1. 6l,
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<br />inches over a three day period. The storm of 1939 produced very little
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<br />runoff in the Yampa Hiver. The storm of September 1970 produced only
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<br />.63 of an inch,of rainfall at Steamboat Springs.
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<br />Based on the preceeding information a standard project general rain storm
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<br />was deve-loped for the Yampa River basin using the September 1970 Four
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<br />Corners storm as a model. That portion of this stOlTh centered over the
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<br />Grand Hesa area ea,st of Grand Junction I~as transposed 'to tlm locations in
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<br />the Yampa River basin - on the lVhite River Plateau and on the Park Ran!le.
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<br />This produced a 40 hour storm with a 3.35 inch rainfall over the Yampa
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<br />River above Agate Creek and a l,..13 inch average rainfall on the Park Range.
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<br />This standard project storm has a frequency of about 250 years if plotted
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<br />on the Steamboat Sprin!ls frequency curve inclosed (see chart 3).
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<br />Loss rates for the basin had to be estimated because of ,the lack of
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<br />reproducible rain flilods i.n the area. A study of runoff in the Grand Besa
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<br />ar.ea during the September 1970 Four. Corner 1 s storm indicated hip,h' initi').l
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<br />(!lreatcr than 1. 5 iIlches) losseD. ^ study.of stt"eam flo"s contained in
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<br />,the U.S. Forest Service publication ^'llll'al _Stre;.'.!"f1~ SlmunClries_ from Four
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