8119

• UCREFRP Catalog Number: 8119
• Author: Valdez, R. A. and B. R. Cowdell.
• Title: Effects of Flow Regulation and Ice Formation on Overwinter Nursery Habitat and Survival of Age-0 Colorado Squawfish in the Green River Below Flaming Gorge Dam - Draft.
• USFW Year: 1996.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

SITE 1 (RM 331.6)

Site 1 was a downstream oriented chute channel formed at the base of a high-water channel in Island
Park (RM 331.6). This backwater had an area of 550 m2 with a maximum depth of 2.0 ft at 1,900 cfs.
Ice formation in this backwater was minimal. Maximum ice formation was in early January, covering
approximately 70 percent of the surface with an average depth of 0.1 in. The backwater was ice free by
February. Dissolved oxygen concentrations were low in January, averaging 3.6 mg/l in the back 50
percent of the backwater. January backwater temperatures averaged 3.10C compared to 0.20C in the
main river. By February backwater temperatures were similar to the mainchannel (backwater averaging
2.70C, mainchannel 2.00C), and D.O. concentrations were above 8.0 mgll throughout the habitat. Even
with the reduced D.O. levels, this area was considered suitable habitat throughout the winter.

Baseline 120 feet

Area 5,941.6205

Bathymetric map of Site 1 (RM 331.6), showing waters edge and 1 ft contour lines.

Photographs of Site 1 (RM 331.6) taken October 1994, (top) and January 1995 (bottom).