ISFAPPC03927

• Case Number: 02CW0281
• Stream Name: Waterfall 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 I: Data

Party Date Q 250%-40% Summer (3/3) Winter (2/3)
DOW/CWCB 10/09/96 3.84 9.6 - 1.5 3.5 2.9

BLM = Bureau of Land Management DOW= Division of Wildlife
(1) 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 3.5 cfs summer flow and a 2.9 cfs winter flow based on the October
9th, 1996, data collection efforts.

Staff reviewed the data collected by the CDOW. The summer flow recommendation for the
reach, which meets 3 of 3 criteria and is within the accuracy range of the R2CROSS model is 3.5
cfs. The winter flow recommendation for the reach which meets 2 of 3 criteria and is within the
accuracy range ofthe R2CROSS model is 2.9 cfs (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 8.5 miles north of the Waterfall Creek drainage. The hydro graph below was
derived from data collected by the USGS stream gage for the San Miguel River near Telluride,
CO (ill #09171200), which has a drainage area of 42.8 square miles. The drainage area of
Waterfall Creek is approximately 3.7 square miles. Staff used a basin apportionment method to
estimate stream flows for Waterfall 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 Waterfall
Creek, in terms of a percentage of exceedence.

Table 2:

Estimated Waterfall Creek Stream Flow
Exceedences
1%
5%
10%
20%
50%
80%
90%
95%
99%

January February March April Mav June Julv AUllust Seotember October November December
1.58 1.76 4.44 9.18 35.56 41.17 36.64 18.07 8.14 4.24 2.94 2.02
1.49 1.67 2.70 7.91 30.67 36.47 31.50 10.61 6.42 3.49 2.55 1.76 I
1.41 1.67 2.06 6.86 20.99 31.64 23.62 8.28 5.71 3.34 2.46 1.67
1.41 1.58 1.76 5.36 16.24 27.24 17.68 6.68 4.92 2.90 2.29 1.58
1.32 1.32 1.41 3.08 10.46 20.39 8.52 4.48 3.25 2.37 1.93 1.49
1.23 1.23 1.23 1.93 6.15 11.60 4.83 3.43 2.37 2.02 1.76 1.41
1.14 1.23 1.23 1.41 3.83 10.19 3.92 2.90 2.29 1.93 1.67 1.41
1.14 1.23 1.23 1.41 3.19 8.79 3.54 2.55 2.20 1.93 1.67 1.14
1.14 1.23 1.05 1.39 2.55 7.08 2.88 2.37 2.11 1.85 1.58 1.14

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