WSP07315

• File Number: 8220.101.09B
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 4/1/1995
• Title: Comments re: Operation of Glen Canyon Dam Final Environmental Impact Statement
• Water Supply Pro - Doc Type: EIS

1

ASSESSMENT OF CHANGES TO THE
GLEN CANYON DAM
ENVIRONMENTAL IMPACT STATEMENT
PREFERRED ALTERNATIVE
FROM DRAFT EIS TO FINAL EIS

July, 1995
Revised October, 1995

I.

INTRODUCTION

In early 1993 Western Area Power Administration (Western) approached the Glen
Canyon Dam Environmental Impact Statement (EIS) cooperating agencies with a
proposal to change two parameters of the existing interim flow criteria for
Glen Canyon Dam. Those two requests were for:

(1) Increasing the upramp rate from 2,500 cfsjhour to 4,000 cfs per
hour, and

(2) Increasing the maximum flow from 20,000 cfs to 25,000 cfs

Western requested that the Glen Canyon Environmental Studies (GCES) Scientific
Coordination Group evaluate the recommendations. Reclamation and the
cooperating agencies initially. reviewed this issue and unanimously agreed to
propose a deviation from the interim flow criteria to incorporate the change
in these two parameters. Consultations as perscribed in the Grand Canyon
Protection Act were completed, and a recommendation forwarded for
implementation. Concurrent with these efforts, it was. determined by the
Commissioner of Reclamation that the proposed changes should be dealt with in
the EIS process. As a result of this decision, no deviations from interim
flow criteria were implemented. In response to that determination and
guidance, and with input from the public and cooperating agencies on the draft
EIS, the preferred alternative for the final EIS was revised to include the
changes in those two parameters. The revised preferred alternative was
publically discussed for inclusion in the final EIS at the May, June, August,
and November 1994 Cooperating Agencies meetings, and was broadly accepted. by
that group without exceptions being raised by the various interest groups
present. In addition, there were two articles on the revised preferred
alternative in the Fall 1994 EIS Newsletter which was distributed to about
16,000 people .nationwide. The changes were included in the final EIS
alternative analysis of the preferred alternative. The Bureau of Reclamation
(Reclamation) completed the review process through the EIS team with
evaluation by the GCES Scientific Coordination Group led by the Senior
Scientist.

The primary reason for these changes is to benefit hydropower. The Interim
Operating Criteria were based on results from GCES Phase I, professional
judgement, and were designed to be environmentally conservative over the
interim period. With the benefit of the additional GCES Phase II results and