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<br />DRAFT <br /> <br />USGS gaging stations considered in the regional analysis, their <br />associated period of record and drainage areas are identified in <br />Table 2.2 In general, there is a large gap in the size of basins <br />represented for the analysis between the 20 to 90 square mile <br />range. This is the reason, the two basins outside of the Blue <br />River, Half Moon Cr. and Clear Cr., were included. These basins <br />were located at similar elevations as the Blue River Basin. Gaging <br />stations from the Upper Colorado River Basin in Grand County were <br />also investigated, but initial review showed that most were highly <br />influenced by diversions and exhibited different hydrologic <br />characteristics. Therefore, they were not included in the <br />analysis. <br /> <br />The data for the two USGS stations, Blue River "at Dillon" and Blue <br />River "near Dillon", were combined to make a single record form <br />1911 to 1985. This information was analyzed separately form the <br />two individual gages. The combining of the records was achieved <br />by calculating the ratio of the "near Dillon" to the "at Dillon" <br />gage discharges for the 3 years of common record, 1958 - 1960, and <br />multiplying the pre 1958 "at Dillon" discharges by this ratio. The <br />adopted ratio was 0.94. <br /> <br />TABLE 2.2-USGS STATIONS CONSIDERED IN REGIONAL FREQUENCY ANALYSIS <br /> <br />USGS <br />DESCRIPl'ION <br /> <br />Blue River @ Dillon <br />Blue River nr. Dillon <br />Snake R. nr. Montezuma <br />Keystone G. nr. Keystone <br />Tenmile bl. N TM @ Frisco <br />Tenmile Cr. @ Dillon <br />Straight Cr. nr. Dillon <br />willow Cr. nr. Dillon <br />Rock Cr. nr. Dillon <br />Boulder Cr. @ Upper Sta. <br />Boulder Cr. nr. Dillon <br />Slate Cr. Up. Sta. <br />Slate Cr. nr, Dillon <br />Black Cr. bl. Black Lake <br />Black Cr. ab. Green Mtn. <br />Otter Cr. ab. Green Mtn. <br />Cataract Cr. nr. Kremling <br />Cat. Cr. ab Green Mtn. <br />Halfmoon Cr. nr. Malta <br />Clear Cr. ab. <br />Clear Cr. Reservoir <br /> <br />STATION <br />NO. <br /> <br />PERIOD OF DRAIN AREA <br />RETURN (SQ. MI.) <br /> <br />09046600 <br />09046600 <br />09047500 <br />09047700 <br />09005100 <br />09050500 <br />09051500 <br />09051500 <br />09052000 <br />09052400 <br />09052500 <br />09052800 <br />09053000 <br />09054000 <br />09054500 <br />09055000 <br />09055300 <br />09055500 <br />07083000 <br />07086500 <br /> <br />1811-1960 <br />1958-1985 <br />1943-1985 <br />1958-1985 <br />1958-1985 <br />1911-1960 <br />1944-1951 <br />1943-1951 <br />1943-1985 <br />1967-1985 <br />1943-1951 <br />1967-1985 <br />1943-1954 <br />1943-1985 <br />1944-1953 <br />1944-1953 <br />1967-1985 <br />1944-1953 <br />1947-1985 <br />1946-1983 <br /> <br />129. <br />119. <br />57.7 <br />9.1 <br />93.3 <br />Ill. <br />12.8 <br />13.5 <br />15.8 <br />8.6 <br />9.8 <br />14.2 <br />16.6 <br />15.0 <br />18.2 <br />9.4 <br />12.0 <br />14.4 <br />23.6 <br />67.1 <br /> <br />Regional skew coefficients were developed using the procedure <br />outlined in Bulletin #17B. Two separate skew coefficients were <br /> <br />6 <br />