BOARD01594

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

Table I: Field Data

Party Date Q 250%-40% Summer (3/3) Winter (2/3)
BLM 5/21/2002 4.45 11.1-1.8 18.5(1) 3.0
BLM 5/21/2002 4.15 9.6 - 1.5 12.4(1) 4.1
BLM 6/05/2003 24.7 61.8 - 9.9 8.4\') 5.0\')
BLM 6/05/2003 25.1 62.7 - 10.0 18.2 4.4(1)
BLM 5/22/2002 3.89 9.2 - 1.5 14.1 \,) 5.9
BLM 5/22/2002 4.61 11.5 -1.8 10.0 10.0
BLM 6/04/2003 27.4 69.0 - 11.0 33.0 27.0
BLM 6/05/2003 28.9 72.4 - 11.6 22.0 8.1 \,)

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 33.0 cfs to 10.0 cfs (See Table I). Averaging the summer
flow recommendations within range results in a summer recommendation of 21 cfs. The winter
flow recommendations, which meet 2 of 3 criteria and are within the accuracy range of the
R2CROSS model range from 27.0 cfs to 3.0 cfs (See Table I). Averaging the winter flow
recommendations within range results in a winter recommendation of 10 cfs. 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.

Hydrologic Data

After receiving the cooperating agency's biologic recommendation, the CWCB and BLM staff,
conducted an evaluation of the stream hydrology to determine if water was physically available
for an instream flow appropriation. Although there is a substantial amount of streamflow gage
data available for the Uncompahgre Plateau and Glade Park, most of this data is severely
impacted by diversions and irrigation use. This situation makes it difficult to estimate the natural
flow regime for the watersheds on the Plateau. Without specific gage data to evaluate, the next
best approach is a regional equation that estimates annual flow characteristics. The USGS has
developed regional equations (Estimation of Natural Streamflow Characteristics in Westem
Colorado. Water Resources Investigations Report 85-4086. 1985) that apply to the Uncompahgre
Plateau and Glade Park based on basin drainage area, mean annual precipitation, mean basin
elevation and mean basin slope. The report "Uncompahgre Plateau and Glade Park Annual
Hydrograph Estimation" in Appendix C, explains staff's water availability analysis in more
detail. Table 2 below displays the estimated stream flow of Roubideau Creek.

Table 2: Roubideau Creek estimated streamflow.

January
1,9

February
4,1

March
6

April
91

M',
330

June
150

July
7,8

August September October November December
3 2.5 2.3 2.3 2.1

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