7104

• UCREFRP Catalog Number: 7104
• Author: Green, B. and M. Butler.
• Title: Analysis of Channel Maintenance and Flushing Flows in the Colorado River at the Palisade Habitat Site ‎(Appendix B)‎.
• USFW Year: 1987.
• USFW - Doc Type: \
• Copyright Material: NO

Concerning the frequency of the flushing flow, the peak mean daily
flows have been evaluated for the 31 years that are modelled under
this study. The minimum flushing flow of 10,000 cfs was not met in
10 years, and was decreased by the Two Forks project in 3 years.
The Williams Fork project further reduced the peak flow in the same
3 years. The peak flows affected by the projects that were below
10,000 cfs are listed below.

Year
1961
1976
1981

Baseline
8,177
8,310
4,522

~o
Forks
8,145
8,278
4,490

Williams
Fork
7,988
8,124
4,473

The above peak flows are mean daily flows and the corresponding
instantaneous peak flow is typically 200 to 2,000 cfs higher. Thus
the use of mean daily values to analyze the impact on the flushing
flows of 10,000 cfs is conservative. Diversions from the projects
will alter the flooq frequency curve at palisades by increasing the
. ~A

recurrence interval for a given flow. Using the peak mean daily
flows for the 1952 to 1982 period of record and a log-Pearson type
III distribution, a 10,000 cfs flow has a recurrence interval of
1.65 years. The Two Forks project increases the recurrence
interval to 1.66 years and the Williams Fork project increases the
interval to 1.67 years. The increase in recurrence intervals
(longer average time petween flows of same magnitude) at Palisades
from the Two Forks and Williams Forks projects is not appreciable.

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