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

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Maximum stage change occurred when flows of 800 cfs were followed by 4,200 cis for

a duration of 8 hours. This resulted in a stage change of 58 cm at Mitten Park, 46 cm at

Jensen, and 15 cm at Ouray. The 4-hour scenario produced stage changes of 46,37, and 12

cm, respectively. Stage changes for the 1 and 2-hour scenarios were somewhat less. The

attenuation phenomenon was illustrated by diminished total and stage change rate with

distance from the dam, as well as increased time for the change to occur.

Predicted stage change rates under the 8-hour scenario were 7.2 and 6.5 cm/h at

Mitten Park and Jensen, respectively. This rate dissipated to 1.3 cm/h by the time the flow

reached Ouray. Under the 4-hour scenario, rates of 5.7 and 5.2 cm/h were predicted at

Mitten Park and Jensen, respectively. A change in stage caused by this sudden increase in

discharge was expected approximately 24, 38, and 58 hours later at Mitten Park, Jensen

Bridge, and Ouray Bridge, respectively. The rate at which a given change in flow travels

downstream depends on water volume and flow duration preceding as well as following the

change. A greater volume of water following a flow change can essentially push that change

downstream faster. This investigation also showed that frazil ice appeared to slow the

downstream rate of change.

Temperature and Ice Conditions

Ice condItions on the Green River were different during the two winters (Table 2),

primarily because of air temperatures. Winter 1 (1986-87) was warmer than normal with

little ice formation, while Winter 2 (1987-88) was colder than normal with substantial ice

development. Water clarity appeared higher in Winter 2, probably as a result of lower flow