BOARD01186

• Board Meeting Date: 1/25/2005
• Description: ISF Section - Instream Flow Appropriations - Smith Fork Gunnison River
• Board Meetings - Doc Type: Memo

Biologic Plow 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
of 3 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 determine 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 Pork Gunnison River near Crawford, CO (ID #009128500), 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 Pork 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 Pork Gunnison River at the gage, in terms of a percentage of exceedence.

Table 2: Stream Flow in Smith Fork GUllllison River
Exceedences Jan feb mar apr may Jun jul aug sep oct nov dec
10/0 19 22 72.71 306.6 691.1 537 131.7 34 33 36 28 20
50/0 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
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 16.7 5.3 2.6 3 4 4.5 3.9

Estimated Stream Flow on Smith Fork Gunnison

50

10

40

30

2
(j

20

o

Jan feb mar apr may jun jul
Month

aug sep oct nov dec

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