BOARD01016

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

Biological Data

The BLM has conducted field surveys of the fishery resources on this stream and have found a
natural environment that can be preserved. As reported in the letter from BLM to the CWCB
"Fishery surveys indicate that the stream environment is presently in stable condition, and
supports a self-sustaining brook trout and cutthroat trout fishery. Water quality, bank stability,
cover, food supplies and substrate are good for salmonids. This type of stream environment has
steep gradients that typically limit the available pool habitat, and winter icing further limits the
amount of available habitat. Accordingly, it is important to provide stream flows that protect the
limited amount of available habitat if the continued existence of the fishery is to be assured."
(See BLM 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 flow
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 9/29/2003 2.78 7.0 - 1.1 1.6 0.9
BLM 7/17/2003 4.00 9.7 - 1.6 1.3(1) 1.3(1)
BLM 7/17/2003 3.63 9.0 - 1.4 1.5 0.7\')

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

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