9294

• UCREFRP Catalog Number: 9294
• Author: Day, K. S. and C. Crosby.
• Title: Backwater Use by Young-og-the-Year Chub ‎(Gila sp.)‎ and Colorado Squawfish ‎(Ptychocheilus lucius)‎ in Desolation and Gray Canyons of the Green River, Utah.
• USFW Year: 1997.
• USFW - Doc Type: FG-,
• Copyright Material: NO

STUDY AREA.
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Field studies were conducted in the canyon reaches of the middle Green River in eastern
Utah. Two major canyons of differing geology and river characteristics were sampled: Desolation
Canyon (River Kilometers ARK} 345.9-249.4) and Gray Canyon (RK 249.4-212.4). (River
kilometers reported here aze as measured upstream along the Green River from its confluence
with the Colorado River (RK 0)) (Figure 1).
Desolation Canyon is created by the Green River as it cuts southward through the
Tavaputs Plateau. In its upper reaches (RK 345.9-321.8) the canyon is characterized by large,
sweeping amphitheaters alternating with broad side canyon plains and slow, Laminar river flows.
Channel sediments are sand and silt with occasional gravel bars. River banks aze primarily sand
and soil. Backwaters are almost exclusively in sand/silt substrates. Dominant bankside vegetation
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includes sagebrush (Artemesia sp.), greasewood (Sarcabatus vermi~tus), tamarisk (Tamarix
ramosissima), box elder (Ater niger) and cottonwood (Populus sp.). -Below RK 321.8 the
canyon narrows and deepens dramatically. Canyon walls of red sandstone become shear and
reach several hundred meters in height, while overall canyon depth exceeds 1524 meters at its
deepest point. The river gradient steepens greatly and numerous riffies and rapids aze dispersed
throughout the river. Channel substrate changes from sand/silt to an alternating regimen of sand
(in runs and pools) and cobblefrubble/boulders (in riffles and rapids). River banks are either sand
or rubble/boulders associated with debris fans or cliff faces. Debris fans have little, usually
shrubby, vegetation such as sagebrush, and skunkbush sumac (Rhus trilobata). Sandy banks are
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