7333

• UCREFRP Catalog Number: 7333
• Author: Valdez, R. A. and W. J. Masslich.
• Title: Winter Habitat Study of Endangered Fish - Green River, Wintertime Movement and Habitat of Adult Colorado Squawfish and Razorback Suckers.
• USFW Year: 1989.
• USFW - Doc Type: Report No. 136-2 for Bureau of Reclamation,
• Copyright Material: NO

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LIST OF FIGURES

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Study area for winter habitat of adult Colorado squawfish and razorback suckers. . . 2

Flow of the Green River near Jensen for the 2 years preceeding Flaming Gorge Dam and
for the 2 years of this study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Monthly flow exceedance curves of the Green River for 12-year periods before and after
Flaming Gorge Dam. Average monthly nows from USGS records at Greendale. . . .13

Representative average and extreme hourly releases from Flaming Gorge Dam for
January and February of 1987 and 1988, as recorded by WAPA. . . . . . . -. . . . . 14

Changes in stage of the Green River at three locations downstream from Flaming
Gorge Dam, under four time-release scenarios, 1, 2. 4, and 8 hours at 4200 cfs following

a low flow of 800 cfs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Average maximum and minimum air temperatures for the winters of 1986-87 and 1987-
88, compared to normal temperatures (historical means), as recorded at the NOAA
weather station in Jensen, UT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18'

Water temperature of the Green River for the winters of 1986-87 and 1987-88, as
recorded at the USGS stream gage near Jensen, UT. Values are instantaneous
measurements taken once daily by an observer. 19

A longitudinal view of the Green River from Flaming Gorge Dam to Ouray with associated
gradient and ice formation during January and February, 1988. . . . . . . . . . . . . 22

Hypothetical cross-section of ice development on the Green River between RM 305 and
316, from December to late February, 1988. 26

Net upstream and downstream movement of adult radiotagged Colorado squawfish in

1986-87 and 1987-88. .................................... 30

Net upstream and downstream movement of adult radiotagged Razorback suckers in

1986-87 and 1987-88. ..................................... 32

Habitat used by overwintering adult radiotagged Colorado squawfish and razorback
suckers in the Green River under ice and ice-free conditions, SA= backwater, ED =
eddy, RU = slow run, SW = slackwater. ......................... 34

The relationship between rate of stage change and rate of fish movement of two adult
Colorado squawfish and four adult razorback suckers in the Green River . . . . . . 38

Movement of 2 adult radiotagged Colorado squawfish and 1 razorback sucker following
the scheduled flow release of January 6, 1988, as seen on JanuarY 7, 1988, at Rainbow

Park (AM 329.5). ....................................... 39

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