9350

• UCREFRP Catalog Number: 9350
• Author: Hawkins, J., T. Modde and J. Bundy.
• Title: Ichthyogauna of the Little Snake River, Colorado, 1995 with Notes on Movements of Humpback Chub.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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STUDY AREA

Headwaters of the Little Snake River originate in northwestern Colorado and
south-central Wyoming and drain portions of two very different physiographic
provinces, the Southern Rocky Mountains and the arid Wyoming Basin. These
drainages influence form and function of downstream fish habitat. Within
Colorado, we divided the Little Snake River into three major reaches distinguished
by topography, geology, gradient, and predominant substrate types. In each reach,
we sampled an 8-km site that was also sampled by Hawkins et al. (1997)
Locations were identified by their distance in river kilometers (RK) from the Yampa
River. A description of each site and reach follows (Figure 1).

From the state line at RK 1 60 to RK 80 (upper reach) the river contains riffle-
pool sequences with mostly gravel and cobble substrate that provide diverse fish
habitat. During runoff, riffles, pools, and eddies were common as were large, deep
refugia pools at base flow. The specific fish sampling site was near Moffat County
Road-147 between RK 103 and RK 95.

The river continues through a broad, unconfined channel with low gradient
and mostly sand substrate in the middle reach from RK 80 to RK 15. Diversity of
fish habitat in this reach was low at all water levels. During runoff, fish habitat
was mostly homogeneous runs with few eddies. During baseflow, fish habitat was
marginal or non-existent because flow dispersed through the broad, sand bed. The
specific fish sampling site in this reach was between RK 69 and RK 61 near Moffat
County Road-26.

The lower reach was from RK 15 to RK O. At RK 15, the river enters a
5.5 km-Iong, bedrock canyon that constricts the channel, increases gradient, and