ISFAPPC01670

• Case Number: 02CW0280
• Stream Name: Swamp Canyon Creek
• Watershed: San Miguel River
• Water Division: 4
• Water District: 60
• County: San Miguel
• Instream Flow App - Doc Type: Supplemental Data

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Table 1: Data
Part
DOW/CWCB

Winter 2/3
1.4

Q
5.1

250%-40%
12.7 - 2.0

Date
10/9/96

BLM = Bureau of Land Management DOW = Division of Wildlife
(I) Predicted flow outside of the accuracy range of Manning's Equation.

CWCB = Colorado Water Conservation Board
? = Criteria never met in R2CROSS Staging Table_

Biologic Flow Recommendations
The CDOW recommended a 3.0 cfs summer flow and a 1.4 cfs winter flow for the segment
based on the October 9th, 1996, data collection efforts.

Staff reviewed the data collected by the CDOW. The summer flow recommendation for the
upper reach, which meets 3 of 3 criteria and is within the accuracy range of the R2CROSS model
is 3.0 cfs. The winter flow recommendation which met 2 of 3 criteria falls outside of the
accuracy range of the R2CROSS model (See Table 1). It is our belief that recommendations that
fall outside of the accuracy range of the model, over 250% of the measured discharge or under
40% of the measured discharge may not give an accurate estimate of the necessary instream flow
required. In these cases, CWCB staff relies upon the biological expertise of the cooperating
agencies to develop a biologic instream flow recommendation.

To determine the winter flow recommendation, staff considered the proposed winter
recommendation for Swamp Canyon Creek of 1.4 cfs. After consulting with the Colorado
Division of Wildlife, staff believes 1.4 cfs will be sufficient to protect the natural environment to
a reasonable degree, if water is available (See Table 1).

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. There are no currently operated or historically operated
streamflow gages for this reach. The closest gage CWCB staff found was the gage located on the
San Miguel River 7.6 miles northwest of Swamp Canyon Creek drainage. The hydro graph below
was derived from data collected by the USGS stream gage for the Howard's Fork San Miguel
River near Telluride, CO (ID #09171200), which has a drainage area of 42.8 square miles. The
drainage area of Swamp Canyon Creek is approximately 2.5 square miles. Staff used a basin
apportionment method to estimate stream flows for Swamp Canyon Creek (See Gage Summary
in Appendix C). The period of record for this gage was 1959 to 1965, the period of record used
by staff in their analysis was 1959 - 1965, or six years of record. Table 2 below displays the
estimated flow of Swamp Canyon Creek above the Howard's Fork San Miguel River, in terms of
a percentage of exceedence.

Table 2:

Estimated Swamp Canyon Creek Stream Flow
Exceedences F
1%
5%
10%
20%
50%
80%
90%
95%
99%

Jan uarv ebruarv March ADril Mav June Julv August September October November December
1.07 1,19 3.00 6.20 24.03 27.81 24.76 12.21 5.50 2.87 1.98 1_37
1.01 1.13 1.82 5.34 20.72 24.64 21.28 7.17 4.33 2.36 1.72 1.19
0.95 1.13 1.39 4.63 14.18 21.38 15.96 5.59 3.86 2.26 1.66 1_13
0.95 1.07 1.19 3.62 10.97 18.41 11.95 4.51 3.33 1.96 1.54 1.07
0_89 0.89 0.95 2.08 7.07 13.78 5.76 3.03 ' 2.20 1.60 1.31 1.01
0.83 0.83 0.83 1.31 4.16 7.84 3.27 2.32 1.60 1.37 1.19 0,95
0.77 0.83 0.83 0.95 2.59 6.89 2.65 1.96 , 1.54 1_31 1,13 0.95
0.77 0.83 0_83 0.95 2.16 5.94 2.39 1.72 1.48 " 1.31 1.13 0.77
0.77 0.83 0.71 0.94 1.72 4.79 1.94 1.60 ' 1.43 1.25 1.07 0.77