BOARD00148 ‎(2)‎

• Board Meeting Date: 3/12/2007
• Description: WSP Section - Colorado River - DEIS - Development of Lower Basin Shortage Guidelines and Coordinated Management Strategies for Lake Powell and Lake Mead, Particularly Under Low Reservoir Conditions
• Board Meetings - Doc Type: Memo

Environmental Consequences

executive Summary

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ES.1.4.1 No Action Alterna "ve
The No Action Alternative provide1s a baseline for comparison of each of the action
alternatives. Tht~ No Action Altern~tive represents a projection of future conditions that
could occur during the life of the pfoposed federal action without an qction alternative
being implemented. I
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Pursuant to the Long-Range Opera~ng Criteria (LROC), the Secretary makes a number
of determinations at the beginning 9f each operating year through the development and
execution of the AOP, including the water supply available to users in the Lower Basin
and the annual release from Lake P?well. However, the LROC currently does not include
specific guidelines for such determinations. Furthermore, there is no actual operating
experience under very low reservoit conditions, i.e., there has never been a shortage
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determination in the Lower Basin. lfberefore, in the absence of specific guidelines, the
outcome of the annual determination in any particular year in the future cannot be
precisely known. However, a reasorlable representation of future conditions under the No
Action Alternative is needed for corhparison to each action alternative. The modeling
assumptions used for this represend,tion are consistent with assumptions used in previous
environmental compliance documents for the ISO, the Colorado River Water Delivery
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Agreement, and the Lower Colorado River Multi-Species Conservation Program (LCR
MSCP). However, the assumptions ~sed in the No Action Alternative are not intended to
limit or predetermine these decision~ in any future AOP determination.
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ES.1.4.2 Basin States Alterniltive
The Basin States Alternative was de~eloped by the Basin States and proposes a
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coordinated operation of Lake Powell and Lake Mead that would minimize shortages in
the Lower Basin and avoid risk of crirtailments of Colorado River water use in the Upper
Basin. This alternative includes sh0l1ages to conserve reservoir storage; coordinated
operations of Lakes Powell and Mea<l determined by specified reservoir conditions; a
mechanism for the storage and delivJry of conserved system and non-system water in
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Lake Mead; and a modification and extension of the ISO through 2026.
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ES.1.4.3 Conservation Before Shortage Alternative
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The Conservation Before Shortage Alternative was developed by a consortium of NO Os.
The Conservation Before Shortage Alternative includes voluntary, compensated
reductions (shortages) in water use tol minimize involuntary shortages in the Lower Basin
and avoid risk of curtailments of Colbrado River water use in the Upper Basin. This
alternative includes voluntary shortag,es prior to involuntary shortages; coordinated
operations of Lakes Powell and Mearl; determined by specified reservoir conditions; an
expanded mechanism for the storage ~nd delivery of conserved system and non-system
water in Lake Mead, including water for environmental uses; and a modification and
extension of the ISO through 2026. '

ES.1.4.4 Water Supply Alternative
The Water Supply Alternative maximizes water deliveries at the expense ofretain~ng
water in storage in the reservoirs for future use. This alternative would reduce water
deliveries only when insufficient watet to meet entitlements is available in Lake Mead.
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When reservoir conditions are relatively low, Lakes Powell and Mead would share water

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February 2007

, ES-6

Draft EIS - Colorado River Interim Guidelines for
lower Basin Shortages and Coordinated Operations
for Lake Powell and Lake Mead