8128

• UCREFRP Catalog Number: 8128
• Author: U.S. Bureau of Reclamation.
• Title: Operation of Glen Canyon Dam\
• USFW Year: 1995.
• Copyright Material: NO

Description of Alternatives
Endangered Fish
Research Further studies of the linkages between endangered fish, their habitat, and
Colorado River flows which were a part of this alternative in the draft EIS
have been moved to the scientifically based Adaptive Management
Program (see "Common Elements").
Interim Low Fluctuating Flow Alternative
Minimum Maximum Allowable daily Ramp
releases releases fluctuations rate
(cfs) (cfs) (cfs/24 hrs) (cfs/hr)
8,000 between 20,000 5,000 2,500 up
7 a.m. and 7 p.m. 6,000 or 8,000 1,500 down
5,000 at night
Daily and Hourly
Operations
The Interim Low Fluctuating Flow Alternative was developed to reduce
daily flow fluctuations to well below no action levels, with the goal of
protecting or enhancing downstream resources while allowing limited
flexibility for power operations. This alternative would have the same
annual and monthly operating plan as the No Action Alternative but
would restrict daily and hourly operations as much as or more than any
alternative allowing fluctuating flows. This alternative is the same as the
Interim Operating Criteria implemented on November 1, 1991 (except for
the addition of the common elements). Parameters such as minimum
flows, maximum flows, ramp rates, and allowable daily fluctuations were
designed to protect downstream resources until completion of the final EIS
and ROD.
Minimum flows would be no less than 8,000 cfs between 7 a.m. and 7 p.m.
and 5,000 cfs at night. The maximum rate of release would be limited to
20,000 cfs during fluctuating hourly releases. Any releases greater than
20,000 cfs (other than for emergencies) would be steady on a daily basis
and would be made in response to high inflow and storage conditions.
Ramp rates would be limited to 2,500 cfs/hour for increasing flows and
1,500 cfs/hour for decreasing flows. The limit on daily fluctuations often
would be more restrictive than the minimum and maximum flow rates.
Fluctuations would be limited during any 24-hour period, depending on
monthly release volumes.
Glen Canyon Dam EIS Summary 27