7848

• UCREFRP Catalog Number: 7848
• Author: Burdick, B. D.
• Title: Minimum Flow Recommendation For Passage Of Colorado Squawfish And Razorback Sucker In The 2.3-Mile Reach Of The Lower Gunnison River
• USFW Year: 1997.
• USFW - Doc Type: Redlands Diversion Dam To The Colorado River Confluence.
• Copyright Material: NO

Specific objectives were to:
1. retrieve and summarize former data on capture, positive sightings, and
locations used by radiotagged Colorado squawfish in the plunge pool
immediately downstream of the Redlands Diversion Dam (RM 3.0) and in
the 2.2-mile reach downstream of the Redlands Diversion Dam and
correlate these data with flows during the dates of occupancy,
2. obtain seasonal distribution information for sub-adult and adult
Colorado squawfish from March to October in the plunge pool and in the
2.2-mile reach,
3. obtain microhabitat use by sub-adult and adult Colorado squawfish
including depth, velocity, and substrate,
4. correlate catch rates of native and nonnative fishes with various
water depths and flows, and
5. obtain empirical water depth profiles across various transects during
low-flow periods identified by the hydrological model and by direct
observation as having critical water depths for passage of sub-adult
and adult Colorado squawfish.
STUDY AREA
General
The Gunnison River, a major tributary to the upper Colorado River, arises
at the junction of the East and Taylor rivers near Almont in southwest Colorado.
It flows for about 150 miles, primarily in a west-northwest direction, before it
empties into the Colorado River at Grand Junction. The basin derives its water
supply primarily from the large snow packs that accumulate in the high mountains
during the winter.. The Gunnison River watershed includes the West Elk Mountains,
northern San Juan Mountains, the southern portion of the Grand Mesa, and the
eastern side of the Uncompahgre Plateau. The Gunnison River drains about 7,928
square miles (Wi 1 tzi us 1978) and contributes approximately 1.85 X 106 AF of water
or about 14 percent of the total average annual runoff of the Colorado River
measured at Lees Ferry, Arizona (Cooper and Severn 1994). Between 1970 and 1996,
it contributed about 40 percent of the total average annual flow to the Colorado
River at the confluence of the two rivers at Grand Junction (Personal
communication, Mike Whiteman, USGS).
As is typical of tailwaters below large dams, the river downstream of
Crystal Dam is too clear and too cold to support warmwater endangered fish.
These cold waters extend downstream to the confluence with the North Fork where
water temperatures are somewhat ameliorated.
Lower Gunnison River (2.3-Mile Reach)
A fishery investigation was completed for 75 miles of the Gunnison River
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