BOARD01888

• Board Meeting Date: 1/27/2004
• Description: ISF Section - Instream Flow Appropriations - Green Creek
• Board Meetings - Doc Type: Memo

Table I: Data

Party Date Q 250%-40% Summer (3/3) Winter (2/3)
CD OW 9/17/2003 3.41 8.6 - 1.4 3.0 1.5
CD OW 9/17/2003 3.03 7.7 - 1.2 6.3 1.5
BLM 4/03/2003 3.31 8.2 - 1.3 2.7 1.8
BLM 4/03/2003 2.86 7.1-1.1 2.2 1.9
CD OW 7/12/2000 6.22 15.5 - 2.5 3.6 2.6
CD OW 9/17/2003 3.82 9.6 - 1.5 4.2 1.4\')
CD OW 9/17/2003 3.16 7.9 - 1.3 5.3 1.2(1)

ELM = 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 of3 criteria and are within the accuracy range
of the R2CROSS model, range from 6.3 cfs to 2.2 cfs (See Table I). Averaging the seven
summer flow recommendations within range results in a 3.9 cfs summer recommendation. The
winter flow recommendations, which meet 2 of 3 criteria and are within the accuracy range of
the R2CROSS model range from 2.6 cfs to 1.5 cfs (See Table I). Averaging the five winter flow
recommendations within range results in a 1.9 cfs winter 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 hydro graph below was derived from data collected by the
USGS stream gage for Poncha Creek at Poncha, CO (ID #07093000), which has a drainage area
of 56 square miles (See Gage Summary in Appendix C). The total drainage area of the Green
Creek Drainage is approximately 18 square miles. The period of record for this gage was 1911-
1918, the period of record used by staff in their analysis was 1911-1918, or 7 years of record.
Table 2 below displays the estimated stream flow of Green Creek, in terms of a percentage of
exceedence.

Table 2: Estimated Green Creek Stream Flow

Exceedences
1%

5%

Januarv Februarv March April M" June Julv Auaust September October November December
4.19 4.82 6.43 23.27 80.36 64.29 41.14 17.89 11.09 12.21 8.58 4.50
3.21 3.21 5.14 17.36 62.07 55.29 34.71 13.55 7.07 10.61 7.07 3.86
2.89 2.89 4.24 11.89 49.18 47.25 26.42 11.89 6.43 7.213 5.14 3.63
2.57 2.70 3.54 8.36 42.11 41.79 14.85 8.04 4.18 4.18 3.54 3.21
2.25 2.25 2.57 6.11 23.79 26.68 8.36 5.14 2.89 2.57 2.25 2.25
0.% 1.29 0.96 3.86 12.86 18.00 6.43 3.54 1.93 1.93 1.29 1.13
0.64 0.64 0.96 2.89 7.71 13.82 5.14 2.89 1.93 1.61 1.29 0.%
0.64 0.64 0.64 2.57 6.43 11.25 4.82 2.25 1.54 1.29 1.29 0.80
0.64 0.64 0.32 1.16 5.79 8.71 4.18 1.77 1.13 1.01 0.80 0.48

10%
20%
50%
80%
90%
95%
99%

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