4-06CW230 Anthracite Creek Supplemental Data

• Case Number: 06CW0230
• Stream Name: Anthracite Creek
• Watershed: Gunnison
• Water Division: 4
• Water District: 40
• County: Gunnison
• Instream Flow App - Doc Type: Supplemental Data

Table 1: Data
Party
Date
Q
250 % -40%
Summer (3/3)
Winter (2/3)
CDOW
08/21/1980
45.3
113 - 18.1
36.1
33.7
CDOW
10/29/1985
74.6
187 - 29.8
96.0
66.0
CDOW
10/21/1998
28.2
70.4 - 11.3
31.3
16.8
BLM = Bureau of Land Management DOW = Division of Wildlife
(1) Predicted flow outside of the accuracy range of Manning's Equation. ? = Criteria never met in R2CROSS Staging Table.
Biologic Flow Recommendation
The summer flow recommendations, which meet 3 of 3 criteria and are within the accuracy range
of the R2CROSS model, range from 96 cfs to 31.3 cfs (See Table 1). The winter flow
recommendations, which meet 2 of 3 criteria and are within the accuracy range of the R2CROSS
model, range from 66 to 16.8 cfs (See Table 1). Averaging the three summer flow
recommendations within range, results in a 54 cfs recommendation. Averaging the three winter
flow recommendations within range, results in a 39 cfs recommendation.
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 Anthracite Creek near Somerset, CO (ID #09132050), which has a
drainage area of 94.6 square miles (See Gage Summary in Appendix C). The total drainage area
of this segment of Anthracite Creek is approximately 132 square miles. The period of record for
this gage was 1977 -1981, the period of record used by staff in their analysis was 1977 -1981, or 5
years of record. Table 2 below displays the stream flow of Anthracite Creek, in terms of a
percentage of exceedence.
Table 2: Estimated Stream Flow on Anthracite Creek
Exceedences Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1% 31.8 30.6 170.4 617.6 3380.0 1690.0 855.6 109.3 50.5 43.5 32.8 26.8
5% 21.0 23.0 63.0 505.0 1622.0 1560.0 536.0 91.8 44.0 30.5 26.0 21.8
10% 20.0 22.0 48.2 466.0 1444.0 1400.0 465.0 82.5 38.0 27.0 26.0 21.0
20% 19.0 20.0 38.0 350.0 1082.0 1150.0 350.0 72.0 32.0 25.0 24.0 20.0
50% 17.0 17.0 27.0 190.0 622.0 938.0 138.5 41.0 25.0 20.0 20.0 19.0
80% 15.0 16.0 21.0 41.0 263.2 585.0 39.0 22.0 20.0 17.0 17.0 16.0
90% 14.0 15.0 20.0 32.0 217.0 225.0 24.5 19.0 19.0 17.0 16.0 15.0
95% 14.0 14.0 19.0 28.0 182.0 191.0 23.0 18.0 18.5 16.0 15.0 14.0
99% 12.2 13.0 18.0 25.2 162.7 141.4 21.0 16.0 17.0 14.0 15.0 12.5
4