ISFAPPC01074

• Case Number: 05CW0250
• Case Number: 05CW0251
• Stream Name: Escalante Creek
• Watershed: San Miguel
• Water Division: 4
• Water District: 40
• County: Mesa
• Instream Flow App - Doc Type: Supplemental Data

Table I: Data for U er Reach
Par Date Q
BLM and 06/17/2003 3.18
CDOW
BLM 06/02/2004 11.55

250%-40%
1.3 cfs - 8.0 cfs

Summer
16.24

Winter 2/3
2.54

4.6 cfs - 28.9 cfs

11.47

4.61

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.

Table 2: Data for Lower Reach
Pa Date Q 250%-40% Summer Winter 2/3
BLM and 06/17/2003 6.11 2.4cfs-15.3 cfs 21.14 7.10
CDOW
BLM and 06/17/2003 8.34 3.3 cfs - 20.9 cfs 8.73 7.48
CDOW
BLM 06/02/2004 18.59 7.4 cfs - 46.5 cfs 7.69 6.56

BLM Bureau of Land Management now Division of Wildlife
(I) Predicted flow outside ofthe accuracy range of Manning's Equation. ? = Criteria never met in R2CROSS Staging Table.

Biologic Flow Recommendation - Upper Reach
The summer flow recommendation, which meets 3 of 3 criteria and is within the accuracy range
of the R2CROSS model is 11.5 cfs (See Table I). The winter flow recommendation, which
meets 2 of 3 criteria and is within the accuracy range of the R2CROSS model is 3.2 cfs (See
Table I). The winter recommendation was derived by averaging the results of the two cross
sections. 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.

Biologic Flow Recommendation - Lower Reach
The summer flow recommendation, which meets 3 of 3 criteria and is within the accuracy range
of the R2CROSS model is 8.2 cfs (See Table I). The summer recommendation was derived by
averaging the results of the two cross sections which had flow recommendations within the
accuracy range of the model. The winter flow recommendation, which meets 2 of 3 criteria and
is within the accuracy range of the R2CROSS model is 7.3 cfs (See Table I). The winter
recommendation was derived by averaging the results of the two cross sections within the
accuracy range of the model. 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 ;:stimate 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 Western
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