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

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Figure I-l.

Figure I-2.
Figure II-1.

Figure III-l.

Figure IV-l.

Figure IV-2.

Figure IV-3.

Figure IV-4.

Figure V-l.

Figure V-2.

LIST OF FIGURES

The Colorado River watershed
showing the Upper and Lower Basins,
drainages, dams and impoundments 2

GCES study area . . . . . . .

3

The GCES occurred (1983-1986)
during a transition from
nearly continuous fluctuating
flows to more frequent steady,
high releases and flood releases . 13

Composite illustration of the
critical resources in the Grand
Canyon . . . . . .. ..... 19

Flow volume, sediment load, and
water temperature from low- and
high-water years prior to dam
construction, measured at the
USGS gaging station at Lees Ferry . 24

Flow volume, sediment load, and
water temperature from a low- and
"high-water year following dam
construction, measured at the
USGS gaging station at Lees Ferry . 26

Regulation of river flows has
significantly changed the
distribution of vegetation and
sediment along the riverbanks . . . 28

Banks and sandbars that were
bare prior to dam construction
(top) have become covered with
riparian vegetation (bottom) ... 29

Water is released from Lake
Powell through the powerplant,
the river outlet works, or the
spillways . . . . . . . . . . . . . 32

The forecast error for the total
annual runoff into Lake Powell is
reduced as the actual runoff
progresses . . . . . . . . . . . . 37