WSP08399

• File Number: 8220.101.10
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 10/22/1998
• Title: Briefing Paper on Grand Canyon Adaptive Management Program
• Water Supply Pro - Doc Type: Report/Study

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Powell through the installation of 4.5 ft. spillway gate extensions at Glen
Canyon Dam
. Because flood frequency reduction measures were not needed any more
Reclamation recommended the postponement of the installation of the
gate extensions. The TWG, AMWG and the Basin States agreed to
Reclamation's recommendation. Recommendation is being sent to the
Secretary for approval.
Selective Withdrawal Structure
. As part of its Biological Opinion on the operation of Glen Canyon Dam
the FWS recommend that the Bureau study the feasibility of installing a
selective temperature withdrawal structure on the dam. The purpose is to
provide warm water releases for the Humpback Chub at the Little
Colorado River,
. Reclamation has prepared a draft planning analysis and an Environmental
Assessment (EA) which will be available for public review and comment
in December 1998. A pre-draft was reviewed by the TWG, and Colorado
provided comments.
. Need assurance that any negative impacts can be reversed or mitigated
before TWG/AMWG approves Planning Analysis and EA
Endangered Species Protection
. Humpback Chub - A single population exists at the confluence of the
Lower Colorado River. The Biological Opinion requires the establishment
of a second population,
. Kanab Amber Snail- A single population exists at Vaseys Paradise. The
Biological Opinion requires establishment of a second population. The
second population is now being established by the NPS, FWS, ADFG,
The environmental compliance for the KAS is a major problem.
. SW Willow Fly Catcher - The SWWFC is not a significant issue. The.
general consensus is that the operation of GCD does not impact the
SWWF. The SWWF is a Lake Mead issue.
. Bald Eagle/Peregrine Falcon - are not issues

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