Stream: Tabeguache Creek ‎(Upper Segement)‎ Executive Summary

• Description: Stream: Tabeguache Creek ‎(Upper Segement)‎ Executive Summary
• State: CO
• Water Division: 4
• Title: Stream: Tabeguache Creek ‎(Upper Segement)‎ Executive Summary
• Water Supply Pro - Doc Type: Report/Study

Biological Data
Most of the upper segment is a moderate gradient stream within a confined canyon that allows
for some channel movement during high flow events. The substrate consists mostly of cobbles
that are regularly moved during high flow events. The narrowleaf cottonwood - sandbar willow -
skunkbrush sumac riparian community is vigorous, and shows evidence of new riparian
recruitment on sand bars that are formed during high flow events. The upper reach supports a
beaver community, and beaver ponds on side channels are common. Fishery surveys indicate
that this part of reach provides habitat for a self - sustaining rainbow trout and speckled dace
populations.
Field Survey Data
BLM and CDOW 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.
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 stream, four 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. It is believed 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.
Table 1: Data
Party
Date
Q
250 % -40%
Summer 3/3)
Winter (2/3)
BLM/DOW
6/19/2003
2.51
6.3-1.0
out of range
2.86
BLM/DOW
6/19/2003
2.13
5.3-0.9
out of range
1.80
BLM/DOW
6/2/2006
8.1
3.2-20.2
3.89
out of range
BLM/DOW
6/2/2006
8.09
3.2-20.2
5.62
out of range
-3-