4-04CW160 Supplemental Data

• Case Number: 04CW0160
• Stream Name: North Fork West Creek
• Watershed: Lower Dolores River
• Water Division: 4
• Water District: 63
• County: Mesa
• Instream Flow App - Doc Type: Supplemental Data

the channel, which resultsZii low quantities of pool habitat." (See W Fish Survey in Appendix
B).
Field Survey Data
BLM staff used the R2Cross methodology to quantify the amount of water required to preserve
the natural environment to a reasonable degree. The R2Cross method requires that stream
discharge and channel profile data be collected in a riffle stream habitat type. Riffles are most
easily visualized, as the stream habitat types that would dry up first should streamflow cease.
This type of hydraulic data collection consists of setting up a transect, surveying the stream
channel geometry, and measuring the stream discharge. Appendix B contains copies of field
data collected for this proposed segment.
Biological Flow Recommendation
The CWCB staff relied upon the biological expertise of the cooperating agencies to interpret
output from the R2Cross data collected to develop the initial, biologic instream now
recommendation. This initial recommendation is designed to address the unique biologic
requirements of each stream without regard to water availability. Three instream flow hydraulic
parameters, average depth, percent wetted perimeter, and average velocity are used to develop
biologic instream flow recommendations. The CDOW has determined that maintaining these
three hydraulic parameters at adequate levels across riffle habitat types, aquatic habitat in pools
and runs will also be maintained for most life stages of fish and aquatic invertebrates (Nehring
1979; Espegren 1996).
For this segment of stream, three data sets were collected with the results shown in Table 1
below. Table 1 shows who collected the data (Party), the date the data was collected (Date), the
measured discharge at the time of the survey (Q), the accuracy range of the predicted flows
based on Manning's Equation (240% and 40% of Q), the summer flow recommendation based
on meeting 3 of 3 hydraulic criteria and the winter flow recommendation based upon 2 of 3
hydraulic criteria.
Table 1: Data
Party
Date
Q 250 % -40%
Summer (3/3) Winter (2/3)
BLM
6/23/1997
3.96 9.9-1.6
3.7 0.5
BLM
8/8/2001
0.34 0.1-0.9
? 0.8
BLM
5/15/02
1.80 0.7-4.5
0.5 (t) ?
BLM = Bureau of Land Management
(1) Predicted flow outside of the accuracy
DOW = Division of Wildlife
range of Manning's Equation.
? = Criteria never met in R2CROSS Staging Table.
Biolol?ic Flow Recommendation
The summer flow recommendation, which meets 3 of 3 criteria and is within the accuracy range
of the R2CROSS model is 3.7 cfs (See Table 1). The winter flow recommendation, which meets
2 of 3 criteria and is within the accuracy range of the R2CROSS model is 0.8 cfs (See Table 1).
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.
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