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
Scheduled annual and monthly release volumes would be determined
using essentially the same considerations described under the No Action
Alternative. Beach/habitat-building flows would modify monthly release
volumes when Lake Powell is drawn down.
Habitat maintenance flows-short-term high releases during the spring-
are included in the Moderate and Modified Low Fluctuating Flow
Alternatives to transport and deposit sand for maintaining camping
beaches and fish habitat. These maintenance flows were not included in
the other restricted fluctuating flow alternatives for the following reasons.
With habitat maintenance flows, the High Fluctuating Flow Alternative
would, over the long term, move more sand than supplied by tributaries
and would result in net erosion. Maintenance flows were not included in
the Interim Low Fluctuating Flow Alternative in order to preserve the
current interim flow operations for which nearly 3 years of data have been
collected.
High Fluctuating Flow Alternative
Minimum
releases
(cfs) Maximum
releases
(cfs) Allowable daily
fluctuations
(cfs/24 hrs) Ramp
rate
(cfs/hr)
3,000 31,500 15,000 to 22,000 Unrestricted up
depending on
5,000 monthly release 5,000 or 4,000
volume down
8,000 depending
on monthly
volume, firm load,
and market
conditions
The High Fluctuating Flow Alternative was developed to slightly reduce
fluctuating flows, with the goal of protecting or enhancing downstream
resources while allowing flexibility for power operations. Releases would
be tied to hydrology and power system demand. This alternative would
have the same annual and monthly operation plan as described under the
No Action Alternative but would include additional restrictions on daily
and hourly operations. Parameters such as minimum flows, down ramp
rates, and allowable daily fluctuations were designed to provide some
resource protection, but without substantial impacts to hydropower.
Although daily fluctuation limits would be constant within a month, the
minimum and maximum flows might be different each day.
22 Glen Canyon Dam EIS Summary