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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SECTION V: DAK OPERATIONS

This chapter summarizes the'legislated functions of
Glen Canyon Dam and how these functions are served
through the current operation of the dam. Particular
attention is paid to explaining the rationale for the
release patterns that have caused concern about down-
stream impacts--flood and fluctuating releases.
considerably more detail can be found in Appendix D,
Dam Operations.

Glen Canyon Dam and Lake Powell are part of the
Colorado River storage Project (CRSP), which includes
six dams and reservoirs in the Upper Colorado River
Basin and eleven irrigation projects. Glen Canyon Dam
serves the CRSP functions through the storage and
release of water from Lake Powell, which has a total
capacity of 27 maf. There are three ways to release
water from Glen Canyon Dam, as shown in Figure V-1:

(1) Release through the powerplant. Glen Canyon
Powerplant 'has eight generators with a total capacity
of 1,356,000 kilowatts (kW). The combined discharge
capacity of the eight turbines is approximately 31,500
cfs. However, a limit of 31,500 cfs (1,900,000
acre~feet ,monthly) is presently followed. Discharge
through the turbines is the preferred method of re-
lease because electricity and associated revenue~re
produced.

(2) Bypassing the powerplant through the river outlet
works. The capacity of the river outlet works is
15,000 cfs. The river outlet works are used when there
is a need to release more water than can be passed
through the powerplant. They are almost always used in
conjunction with powerplant releases, producing
combined releases ranging from 31,500 cfs to 48,500
cfs.

(3) Spillway releases. Releases through the spillways
bypass both the powerplant and the river outlet works.
The combined capacity of both right and left spillways
is approximately 208,000 cfs. Spillway releases are
made only when there is an urgent need to release large
volumes of water to avoid overtopping the dam, or to
lower the level of Lake Powell. Spillway releases are
avoided whenever possible due to the shorter service
life of the spillways compared to the other release
structures. This brings the total release capacity
from all structures to over 250,000,cfs.

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