7423

• UCREFRP Catalog Number: 7423
• Author: U.S. Bureau of Reclamation.
• Title: Glen Canyon Environmental Studies Draft Report, September 1987.
• USFW Year: 1987.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

section IV:

section V:

Section VI:

Changes Since Dam Construction . . . 23

Pre-Dam River Flows Had Wide
Seasonal Variations In Magnitude,
Sediment Load, And Temperature . . . 23

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Post-Dam River Flows Fluctuate
Frequently, Carry Little Sediment,
And Are Colder . . . . . .. .. 25

other Resources Have Changed In
Response To Changes In The River . . 27

Dam operations . . . . . . . . . . . 31

The Major Operational Goal For
Glen Canyon Dam Is Water Storage
And Delivery To The Lower Basin . . 33

Flood Releases Are A Function Of
Reservoir Level Targets, Uncertainty
In Runoff, And operating Rules For
Handling Increases In Forecast
Runoff . . . . . . . . . . . . . . . 35

Fluctuating Releases Are Made To
Match Electricity Production To
Demand ,And To Sell The Most Power . 38

Impacts Of Current Operations . 43

Current Operations Are Characterized
By Flood Releases And Fluctuating
Releases . . . . . . . . . . . . . . 43

Flood Releases Have Negative
Impacts On Terrestrial Resources
And Recreation . . . . . . . . . . . 48

Fluctuating Releases Have Negative
Impacts On Recreation, Little
Effect on Terrestrial Resources,
And Mixed Effects On Aquatic
Resources . . . . . .. .. 54

Flood Releases Have Greatest
Potential For Long-Term And
Irreversible Impacts . . . . . . . . 58