7628

• UCREFRP Catalog Number: 7628
• Author: Pucherelli, M. J., R. C. Clark and J. N. Halls.
• Title: Green River Backwater Habitat Mapping Study, 1987
• USFW Year: 1988.
• USFW - Doc Type: Interim Report.
• Copyright Material: NO

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Following the installation of Flaming Gorge Dam the abundance of
native fish species, including the Colorado squawfish, has
decreased. Based on.extensive studies (Tyus et ale 1987, Tyus and
McAda 1984), the FWS has concluded that backwaters in the Green
River are important nursery habitat for young-of-the-year Colorado
squawfish. It is believed that maximizing backwater habitat in the
Green River during the summer season may increase the survival rate
of Colorado squawfish young-of-the-year.

This study examined the relationship between flow (cfs) and number
and area of backwaters on five sites in the Green River in utah.
Large scale aerial photography was obtained of each site for seven
different flows. Aerial photographs were interpreted and
incorporated into a digital data base. Tabular summaries were
produced for each site at each flow, and computer generated plots
were produced for specific sites and flows. In addition, a field
study was conducted to verify results and incorporate ground
measurements of specific reference backwaters into the study. The
objective of this study was to establish a data base that will
allow determination of optimum Green River flows for backwater
formation during the summer season.

Methodoloqv

Five study sites were subjectively selected by the FWS and BR in
areas known to contain important backwater habitat for Colorado
squawfish young-of-the-year. site locations are indicated in
Figure 1 - Location Hap, and are described as follows:

Site

Approximate River Mile

Lenqth (miles)

Island Park
Jensen
Ouray
Sand Wash
Hineral Bottom

328.5 - 334.5
303.0 - 310.0
250.5 - 261.5
222.5 - 225.5
51.0 - 57.0

6
7
11
3
6

River mile designations were taken from Evans and Belknap's
Dinosaur River guide (+120 miles), Evans and Belknap's Desolation
River Guide (+120 miles), and Belknap and Belknap's Canyonlands
River Guide. Mile zero is the confluence of the Green and Colorado
rivers.

Seven flows [cubic feet per second (cfs)] were examined for
backwaters at the Island Park, Jensen, Ouray, and Sand Wash sites:
5,260, 2,423, 1,773, 1,687, 1,430, 1,381, and 1,101. Three flows
were examined at the Mineral Bottom site: 3,814, 3,261, and 2,748.
The flows and the dates they occurred at the gauges where they were
measured are listed in Appendix B. Flow measurements for the four
upper sites were taken at the Jensen gauge, and the Mineral Bottom