WSP11280

• File Number: 8220.101.09B
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 12/1/1990
• Author: BOR
• Title: Management Plan for Preparation of Glen Canyon Dam Environmental Impact Statement
• Water Supply Pro - Doc Type: EIS

.

.

.

Extenuating circumstances requiring changes
in the EIS Bchedule will be coordinated with
the cDDperating agencies and cleared through
Reclamation'B top management and with DOl
officials. As lead agency, Reclamation will
advise the public of any required changes.

FORMULATION OF
ALTERNATIVES

The fDCUS of the alternatives analysis is on
the operatiDnal aspects of the dam. ResourceB
of concern, as identified by the public and
involved agencies during the seoping process,
will be the focus of the EIS. In addition to
analyzing the operation of the dam, other
measures may be identified to address
resources of concern.

A conceptual framework for formulation of
alternatives has been created to fOCUB on
"integrated' (or multiple-purpose) alterna.
tives. Selected elements of dam operation, in
addition to an array of nonoperational
measures to address public issues and
concerns, will be combined to formulate a
range of reasonable alternatives.

All alternativeB and mitigation measures
suggested during scoping (as well as those
identified during an Ad-Hoc AlternativeB
Work Session, those suggested by the coope-
rating agencies, and those identified by the
EIS team) will be considered conBiBtent with
CEQ Regulation 1502.14. Alternatives deter-
mined to be suitable for evaluation in detail in
the EIS will be described and analyzed.

An alljustment in flow releases from the dam
would consider the requirements for specific
annual volumes of water to be delivered to the
Lower Colorado River Basin. Operational
alternatives would be outlined for low,
medium, and high water year situations, in a
manner that can be understood by the general
public. Description and analysis of varying
water yearB, including extended drought
periods, will be important. Since Lake Powell

filled in 1980, the vDlumes of downstream
releaBeB have varied from the Bpecified
minimum of 8.23 million to over 21 million
acre.feet per year. More operational
flexibility may exist in medium water years
than in low or high water years. AlBD,
Dperational flexibility can be influenced by
available Lake Powell storage space, time of
year, and inflow. Operational alternatives
could span a range Dfmaximum peaking to
base load (though Beasonally adjusted)
releases.

In addition to elemente of dam operatiDn, the
EIS will consider additional mitigation such
as potential alljustments in plans or activities
of the various agencies, related to conditiDns
downstream for the dam but apart from water
releases.

Additional mitigation may also include
structural and/or reBtorative measures
invDlving direct modificatiDn to the dam or to
specific features of the river or canyon. These
could be comprised of temporary or
permanent actions.

Integrated and/or phased alternatives would
be a combination of operational changes,
management actions, and structural or
restorative measures. Some ofthese could be
applied over an extended period of time.
Several different combination scenarios could
be formulated and analyzed to addresB these
objectives:

. Identification of a phased approach to
implementing changes in operation and
future management.

. Exploration of a concept of not only
minimizing future lOBS of resources
associated with the Colorado River
downstream of Glen Canyon Dam, but
also looking at ways to restore parts of
the ecosystem that have been lost.

. Formulation of a program to adjust to
dynamic future conditions in response
to long-term monitoring.

13