8178

• UCREFRP Catalog Number: 8178
• Author: Anderson, R. and G. Stewart.
• Title: Riverine Fish Flow Investigations.
• USFW Year: 1999.
• USFW - Doc Type: Fort Collins, CO.
• Copyright Material: NO

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resolution, allowing for highly accurate quantification of physical habitat availability. A
spatially explicit flow model may eliminate the need for microhabitat suitability curves
used by IFIM, and also improve biological resolution of the method, Presently, however
2-D modeling is not widely used for fishery applications and is still an unknown
commodity as far as its practicality for instream flow assessment.

The goal of this project is to develop and validate a methodology for determining
instream flow requirements for warm water fish communities in Colorado. The
approach is to determine relationships between habitat availability and flow using a 2-D
flow model to simulate m~so-habitat diversity and abundance over a range of low flows
on several sections of three different rivers. Also fish population and species' life
history data will be collected within each of the study sites to provide habitat use and
preference data to determine relationships between base flows and habitat availability
for native fish species of warm water riverine fish communities.

Results of this study will be compared to instream flow recommendations made
on the Yampa and Colorado Rivers to determine strengths and merits of assumptions
used in other methods. These other studies include Modde et al. (1995) that used native
hydrology (Yampa River), Modde et aI. (1999) that used the inflection point method
(Yampa River) and Osmundson et aI. (1995) that used a videography approach to
determine availability of preferred habitats in the Colorado River.

Study Objectives:

1) Model fish habitat availability on warm water sections of three rivers
(Yampa, Colorado and Dolores) using the established methods (I-D
models) and evaluate the practically of using 2-D flow models to quantify
fish habitat.

2) Determine community structure, density and biomass for fish
assemblages for river reaches listed above.

3) Test for relationships between habitat availability and fish abundance.

4) Develop and validate methodologies that use I-D and 2-D flow models
for the Division of Wildlife to use for minimum instream flow
recommendations for warm water river sections.

STUDY AREA

The study area includes warm water reaches of the Yampa River between River
Mile 59 and 135, from Cross Mountain to the town of Craig, Colorado (Figure 1.). The
Duffy Tunnel station is located at River Mile 109.5, in the lower part of Little Yampa
Canyon. Typically one side of the river is adjacent to a canyon wall which can
contribute large boulders to the river in some sections. In Little Yampa Canyon pool
and run habitat with cover provided by large boulders is fairly common. The Duffy
Tunnel station has a generally flat slope. The Sevens station is located at River Mile
62.5. The river in this reach is typ,ically in a valley flood plain adjacent to grazing