8188

• UCREFRP Catalog Number: 8188
• Author: Muth, R. T., et al.
• Title: Flow and Temperature Recommendations for Endangered Fishes in the Green River Downstream of Flaming Forge Dam.
• USFW Year: 2000.
• USFW - Doc Type: \
• Copyright Material: NO

Filial Report

3-33

September 2000

(RK 418), lower Browns Park (RK 392.8), and lower Lodore Canyon (RK 363.2). It was assumed
that water released from the dam was a constant 130C, consistent with present operations.

Water temperature of the Green River downstream of Flaming Gorge Dam was best
predicted as a function of flow and ambient air temperature (Bestgen and Crist 2000). Ambient air
temperature had a large positive effect on water temperature; flow had a smaller and inversely
proportional effect. The influence of ambient air temperature increased in importance in a
downstream direction. Because ambient air temperature has such a large effect, annual variations in
regional weather patterns may play an important role in determining the thermal regime of the Green
River downstream of Flaming Gorge Dam. However, even though flow has less effect on water
temperature, it can be manipulated through modification of release patterns.

3.5.1.2 Water Temperature in Reach 2

Thermal mixing at the confluence of the Green and Yampa Rivers is seasonally dynamic
and has an important effect on Green River water temperatures. During winter, water released from
Flaming Gorge Dam is warmer than the Yampa River. Although the Yampa River begins to get
warmer in spring, temperature in the Green River remains low and stable as a result of cool Flaming
Gorge Dam releases. From the beginning of spring runoff through mid-summer, the temperature of
the Green River downstream of the confluence is strongly influenced by the temperature of water
flowing from the Yampa River. During late summer, the situation reverses as the temperature is
controlled by the cooler, higher-volume releases from Flaming Gorge Dam.

From the Yampa River confluence, the Green Ri ver flows west into Whirlpool Canyon and
then into Island and Rainbow Parks. Water temperature in Island and Rainbow Parks increases
because the river slows down and spreads out, exposing the water to a large channel and radiant solar
energy. From Rainbow Park, the river drops into Split Mountain Canyon, where it is shaded by
canyon walls and where its water velocity increases. Consequently, the water temperature changes
little through this canyon.

The Green River enters the Uinta Basin near Jensen, Utah. Through this broad alluvial area,
the river spreads out into a wide meandering channel, and, during summer, its water temperature
increases further (Figure 3.14).

3.5.1.3 Water Temperature in Reach 3

The Duchesne and White Rivers join the Green River near Ouray, Utah, but do not
appreciably change the temperature of the Green River. Several kilometers downstream from the
confluence of the Green River with the White and Duchesne Rivers, the Green River enters
Desolation and Gray Canyons, where diel fluctuations in water temperature are moderated by
warmth from the canyon walls radiating to the air and water at night. Downstream from these