9569

• UCREFRP Catalog Number: 9569
• Author: Valdez, R. A.
• Title: Synthesis of Winter Investigations of Endangered Fish in the Green River Below Flaming Gorge Dam.
• USFW Year: 1994.
• USFW - Doc Type: 18-11,
• Copyright Material: NO

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

Daily fluctuating releases are a significant attnbute of Flaming Gorge Dam,

determined largely by power generation. To meet peaking power demand, dam releases are

typically low at night and high in morning and evening. These fluctuating releases are

ameliorated with distance downstream from the dam, and by the influence of major

tributaries, such as the Yampa River.

Average and extreme hourly releases from Flaming Gorge Dam for January and

February of 1987 and 1988 (Figure 5) illustrate a large daily variation in discharge. Flow

was typically lowest between midnight and 0600 hours, and highest between 0800 hours and

2000 hours. These extreme daily operational data indicate that the Green River below

Flaming Gorge Dam experienced a two to five-fold change in daily flow during these two

winters, with maximum change of 800 to 4,000 cfs.

Attenuating or dissipating downstream effects of these flow changes from Flaming

Gorge Dam were determined for four release scenarios, under ice-free conditions, using the

Streamflow Synthesis And Regulation Reservoir (SSARR) model (U.S. Army Corps of

Engineers 1972). This model was used to determine changes in stage (water surface

elevation) at three gaged locations downstream from the dam; Mitten Park (108 kIn, 67

miles below), Jensen Bridge (174 lan, 108 miles below), and Ouray Bridge (260 kIn, 162

miles below) (Figure 6). The four scenarios were based on a release of 800 cfs (23 cms)

followed by 4,200 cfs (119 cms), or maximum powerplant variation, for durations of 1, 2, 4,

or 8 hours. These flows approximated minimum and maximum operational releases from

Flaming Gorge Dam in winter, 1986-87 and 1987-88, and provided conditions to illustrate

maximum changes in stage.

6