BOARD00090 ‎(2)‎

• Board Meeting Date: 11/14/2006
• Description: ISF Section - Contested ISF Appropriation - Arkansas River
• Board Meetings - Doc Type: Hearings

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Biologic Flow Recommendation
The summer flow recommendation, which met 3 of 3 criteria and is within the accuracy range of
the R2CROSS model is 12.9 cfs (See Table I). The winter flow recommendation, which met 2
of3 criteria and is within the accuracy range of the R2CROSS model is 7.7 cfs (See Table I).

Hydrologic Data

After receiving the cooperating agency's biologic recommendation, the CWCB staff conducted
an evaluation of the stream hydrology to detemline if water was physically available for an
instream flow appropriation. The hydrograph below was derived from data collected by the
USGS stream gage for Smith Fork Gunnison River near Crawford, CO (ID #009 I 28500), which
has a drainage area of 42.8 square miles (See Gage Summary in Appendix C). The total
drainage area of this segment of the Smith Fork Gunnison River is approximately 49 square
miles. The period of record for this gage was 1935 to 1994, the period of record used by staff in
their analysis was 1935 - 1994, or 60 years of record. Table 2 below displays the flow of the
Smith Fork Gunnison River at the gage, in terms of a percentage of exceedence.

Table 2: Stream Flow in Smith Fork Gunnison River
Exceedences jan feb mar apr may jun jul aug sep oct noy dec
1% 19 22 72.71 306.6 691.1 537 131.7 34 33 36 28 20
5% 13 14 42 228.5 428.4 344.5 71 23.55 23 27 19 14
10% 9.4 11 32 179 359 275 57.1 19 19 20 15 11
20% 8.22 9.4 19 120 291 176 41 15 14 15 12 9.2
50% 6.5 7 11 58 188 89 22 10 8.5 8.6 8 7
. 80% 5.2 5.5 7.5 24 92 50 13 7.2 5.8 6.4 6.5 5.5
90% 4.8 5 6.4 16 72 35 9.6 5.7 4.8 5.7 5.8 5
95% 4.5 4.6 5.64 13.5 53 26 7.45 4.35 3.9 5.1 5.35 4.8
99% 3.8 4.2 5 8.8 22.58 10.7 5.3 2.6 3 4 4.5 3.9

Estimated Stream Flow on Smith Fork Gunnison

50
40
30
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jan teb mar apr may jun jul aug sep oct nov dec
Month

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