7347

• UCREFRP Catalog Number: 7347
• Author: Wick, E. J. and J. A. Hawkins.
• Title: Observations on Use of the Little Snake River in Colorado, by Endangered Colorado Squawfish and Humpback Chub, 1988.
• USFW Year: 1989.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

state line until it reaches the western tip of Carbon County where it flows
southwest into Colorado toward the Yampa River. The confluence of the Little
Snake and Yampa rivers is 5 river miles upstream of Yampa Canyon in Dinosaur
National Monument. This study was conducted on the lower 35 miles of the
Little Snake River in Moffat County, Colorado. Gradient decreases through
this section at approximately 6 feet per mile. MCR 26 ford is located 34.7
river miles (RMI 34.7) upstream of the Yampa River confluence. From MCR 26
ford (RMI 34.7), downstream to MCR 10 bridge (RMI 8.7) the river meanders
through sandy substrate along interspersed grazing land and irrigated alfalfa
fields. Below MCR 10 bridge the river enters a steep, sandstone canyon at RMI
8.0. The gradient drops abruptly in this steep walled canyon which is
approximately 1 mile long and contains large substrates of boulder, rubble,
and cobble. The river then flows another mile through rock outcroppings in a
less constricted, canyon-like area with occasional braiding of the channel.
Substrate is predominantly cobble and gravel. The river then reverts back to
sand substrate at RMI 6.0 as it meanders through irrigated fields and
cottonwood bottoms to its confluence with the Yampa River.
Radiotelemetry
Colorado squawfish were implanted with radiotransmitters for a winter
habitat study on the Yampa River. These fish were being monitored in the
spring to document timing of migration to the spawning area within Dinosaur
National Monument. Radiotracking methods are outlined in detail in Wick and
Hawkins (1989). Fish were tracked from either four wheel drive vehicle,
canoe, or foot. Tracking occurred in May, June, July, and October.
Fish collections
Fish were collected on five sampling trips in May, June, July, and
October. All fish collections were between Highway 318 bridge (RMI 15.7) and
the confluence with the Yampa River. Most sampling was conducted within the
canyon area (RMI 8.0-6.0) located 0.7 mile downstream of MCR 10 bridge. Adult
fish were collected by 1 inch mesh, 50 or 150 ft trammel net and 3/16 inch
mesh, 30 ft seine. The trammel net was either set in a stationary manner in
eddy and pool habitat or was used as a block net at the downstream end of
pools while fish were herded into it with the seine. Fish were also sampled
with angling; using small spoons, artificial flies, or natural earthworm or
mealworm bait. Larval fish were collected with 1/16 inch mesh seine or.
dipnet. All adult or juvenile fish were identified and released in the field.
Fish were field identified if possible, otherwise they were preserved in 10%
buffered formalin for lab identification at the Larval Fish Laboratory at
Colorado State University. Photos were taken of all endangered species.
Discharge measurements
Cross sections were established at two locations for measuring
discharge. One station was near the U. S. Geological Survey (USGS) gaging
station at MCR 10 bridge (RMI 8.7). The other location was below the canyon
at RMI 4.5. Depth and velocity were measured every foot across the stream
channel with a Marsh-McBirney top-set depth rod and analog velocity meter.
Discharge was calculated from the above measurements using the partial
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