8214

• UCREFRP Catalog Number: 8214
• Author: Modde, T., D. Irving and R. Anderson.
• Title: Habitat Availability and Habitat Use of Endangered Fishes in the Yampa River during Baseflow Periods.
• USFW Year: 1997.
• USFW - Doc Type: Vernal, Utah and Grand Junction, Colorado.
• Copyright Material: NO

Strata 6

Clusters 2 (rm 62.8) and 3 (rm 63.5)

Nine cross sections were surveyed in these two clusters along with depth profiles across two
shallow riffles. The length of the reach was 2, 646 feet. At 132.2 cfs, the mean flow measured in
the field (Table 2), shallow runs were 45%, shallow pools were 38%, and deep runs were 14% of
the total surface area of the reach (Appendix 2, Table 6). No Class I pool habitat was found at any
flow. Shallow habitats dominate this reach at flows below 400 cfs. The primary habitat available
for adult CS in this half mile of river is the deep run.

Cluster 7 (rm 73.3)

Five cross sections were done in this cluster. The sequence was 1,205 feet in length. Discharge
determined by field measurements was 287 cfs (Appendix 2, Table 7). The downstream control
cross section had to be located in a spilt channel, with 267 cfs in the main channel or right bank
(looking upstream) and 20 cfs flowing in the smaller channel around a small island. Flow was in a
single channel for all other cross sections in this sequence.

The run in this sequence was slow, deep and had a maximum depth of7.3 feet (cross section 3)
at the field measured flow (288 cfs). This deep run was at the base of a cliff just downstream of a
bend in the river. The slope of this run was flat and the width/depth ratio was low. A drop in flow
from 288 cfs to one cfs lowers WSL by 2.5 feet at cross section 3. At one cfs, much of this run
modeled to be a Class II pool because depths were still up to 4 feet. The Class II pool is the
dominant habitat type of this sequence at flows between one and 40 cfs (Appendix 2, Table 2).
Percentage of usable habitat increased as flow drop below 60 to one cfs, due to expanded influence
of the Class II pool. At flows over 60 cfs, shallow runs are the most common habitat type.

Cluster 11 (rm 78.8)

There were six cross sections surveyed at this sequence. The reach length was 1,772 ft, and
flow measured in the field was 134.9 cfs (Appendix 2, Table 8). The control cross section was
located upstream of a steep shallow riffle and upstream an exposed bar that split flow into two
channels. Flow in the channel left of the bar was 78 cfs (63%) and was 46 cfs (37%) on the right
(looking upstream). Cross section 2 was located 380 ft above the control and just upstream of a
small flowing side channel (13.5 cfs). The flow of this side channel rejoined the main channel at
the base of the riffle below the control. This was the only option for a control site in this cluster and
in spite of the complex channel morphology, the control cross-section modeled without problems.
Flow was confined within a single channel in all other cross sections in this sequence.

Cross sections 2 and 3 described the lower and the middle of the run, respectively. The distance
between cross sections 2 and 3 is 850 feet and the increase in water surface elevation was 0.03 feet.
This run maintained width and depth at decreased flows and at one cfs, 42% of the sequence was

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