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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preference, movement patterns, reproduction require-
ments, and food habits.

Surveys of 370 white-water guides, 1,151 white-water
boaters, 448 Glen Canyon anglers, and 470 Glen Canyon
day-rafters were conducted to assess the effect of dam
releases on the quality of these recreational
activities. To assess the impact of dam releases on
Grand Canyon and Glen Canyon boating accidents, eight
years of NPS accident records were studied and over
5,000 boats were observed running rapids under
different flow conditions.

Factors affecting transport and storage of sediment in
the river channel were assessed from discharge records
from 1922 to 1984, as well as from 874 discharge mea-
surements and 1,943 suspended sediment and 976
riverbed samples taken during the study. Thirty-six
tributaries were examined in detail to assess the
contribution of sediment to the main channel. The data
from sediment sampling and surveys of river cross sec-
tions were used in the development of predictive models
of sediment transport.

Changes in camping beaches and other sand deposits
along the channel margins were measured at 41 sites
during the study. Characteristics of local river geom-
etry and flow were measured in order to relate changes
in deposits to flows. Surveys of deposits made prior
to the study and historical photographs were examined
to extend the study results in time and to other sites.

Detailed topographic and hydraulic mapping of the
channel and flow in the vicinity of 12 of the largest
rapids yielded information on the flows required to
adjust the coarse debris which forms rapids and on how
waves in rapidS changed with flow.

The results of these studies have been published in
technical reports which are available from the National
Technical Information Service, u.S. Department of
Commerce. Information from the technical reports has
been combined and summarized in the three Subteam
Reports which are provided as appendices to this
document. The Sediment, the Biology, and the
Recreation Subteam Reports each give more detail on the
individual technical studies than is given in the main
body of this report. The Dam Operations summary
provides additional background on the current
operating criteria for Glen Canyon Dam. A glossary can
be found at the :back of this document.

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