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<br />Hydrologic Data
<br />
<br />After receiving the cooperating agency's biologic recommendation, the CWCB staff conducted
<br />an evaluation of the stream hydrology to determine if water was physically available for an
<br />instream flow appropriation. The hydro graph below was derived from data collected by the
<br />USGS stream gage for Badger Creek Lower Station, near Howard, CO (ill #07093775), which
<br />has a drainage area of 106 square miles (See Gage Summary in Appendix C). The total drainage
<br />area of the Thirtyone Mile Creek Drainage is approximately 21.4 square miles. The period of
<br />record for this gage was 1980-2001, the period of record used by staff in their analysis was 1980-
<br />2001, or 21 years of record. Table 2 below displays the estimated stream flow of Thirtyone Mile
<br />Creek, in terms of a percentage of exceedence.
<br />
<br />e
<br />
<br />e
<br />
<br />Table 2: Estimated flow Thirtyone Mile Creek,
<br />
<br />Exceedences
<br />1%
<br />5%
<br />10%
<br />20%
<br />50%
<br />80%
<br />90%
<br />95%
<br />99%
<br />
<br />January Februarv March Anril May June Julv August September October November December
<br />1,02 1.47 2,23 11,17 6,89 3,14 2,89 2,84 1,09 1,23 1,32 1,12
<br />0,89 0,96 1,72 4.41 3,90 2,54 1,62 1,52 0,87 1,07 1,12 0,96
<br />0,76 0,86 1.42 2,13 2,94 2,13 1,32 1,12 0,81 0,95 0,97 0,87
<br />0,66 0,67 1,01 1,52 1,93 1,32 0,95 0,91 0,68 0,82 0,86 0,76
<br />0,53 0,53 0,78 1,01 1,01 0,85 0,62 0,67 0,56 0,63 0.73 0,56
<br />0.40 0.46 0,57 0,82 0,75 0,59 0,52 0,50 0.45 0,53 0,59 0.42
<br />0,35 0.40 0,50 0,69 0,69 0,54 0.47 0.45 0.41 0.49 0,54 0,33
<br />0,32 0,35 0.46 0,63 0,65 0,52 0.45 0.40 0,34 0.47 0,51 0,30
<br />0,21 0,15 0.41 0,52 0,58 0.47 0,41 0,29 0,07 0,19 0.41 0,23
<br />
<br /> Thirtyone Mile Creek Estimated Stream Flow
<br /> 2'
<br /> 1.5
<br />~ 1 / ~
<br />(.)
<br /> ~
<br /> -'
<br /> 0.5 -
<br /> -------------- -------.
<br /> 0
<br /> JAN FEB MAR Affi MAY JUN JLL ALG SEP ocr ~v DEe
<br /> Month
<br />
<br />Table 2 shows that the summer flow recommendation of 1.0 cfs is only available at least 50% of
<br />the time from April 15 to May 14. The summer flow recommendation was further reduced to 0.5
<br />cfs for the time period of May 15 through October 31 based on limited water availability. Table
<br />2 also shows that the winter flow recommendation of 0.35 cfs is available at least 50% of the
<br />time from November 1 through April 14.
<br />
<br />- 4-
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