WSP06774

• File Number: 8282.600.10
• Description: Colorado River Annual Operating Plan
• Basin: Colorado Mainstem
• Date: 12/14/1999
• Author: USDOI/BOR
• Title: 29th Annual Report and 2000 Annual Operating Plan for Colorado River System Reservoirs
• Water Supply Pro - Doc Type: Publication

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2000 DETERMlNA nONS

The AOP provides guidance regarding reservoir storage and release conditions during the
upcoming year, based upon Congressionally mandated storage, release, and delivery eriteria and
determinations. After meeting these requirements, specific reservoir releases may be modified
within these requirements as forecast inflows ehange in response to elimatic variability and to
provide additional benefits coincident to the projects' multiple purposes.

Upper Basin Reservoin

The Operating Criteria provide that the annual plan of operation shall include a determination of
the quantity of water eonsidered necessary to be in Upper Basin storage at the end of the
water year, Taking into eonsideration all relevant factors required by the Operating Criteria, it
has been determined that the active storage in Upper Basin reservoirs forecast for September 30,
2000, exceeds the storage required under Section 602(a) of the Colorado River Basin Project
Act under any reasonable range of assumptions which might be applied. Therefore, "602(a)
Storage" is not the criterion controlling the release of water from Glen Canyon Dam during
water year 2000.

Section 602(a)(3) of the Colorado River Basin Project Act provides for the storage of Colorado
River water in Upper Basin reservoirs that the Seeretary of the Interior finds necessary to assure
deliveries to comply with Articles ill( c) and ill( d) of the 1922 Colorado River Compact, without
impairment to the annual consumptive use in the Upper Basin, Pursuant to Section 602(b), as
amended, the Secretary is required to make this determination after consultation with the Upper
Colorado River Commission and representatives from the three Lower Division States, and after
taking into consideration all relevant factors including historie stream flows, the most critical
period of record, the probabilities of water supply, and estimated future depletions. Water not
required to be so stored will be released from Lake Powell:

to the extent it can be reasonably applied in the States of the Lower Division to the uses
specified in Article ill(e) of the 1922 Colorado River Compact, but these releases will not
be made when the active storage in Lake Powell is less than the active storage in Lake
Mead,

to maintain, as nearly as practieable, active storage in Lake Mead equal to the aetive
storage in Lake Powell, and

to avoid anticipated spills from Lake Powell.

Spill avoidance and/or storage equa1ization criterion in accordance with Article 11(3) of the
Operating Criteria will control the releases from Glen Canyon Dam during water year 2000 unless
the minimum objective release criterion in Article 11(2) is controlling. Under the most probable
inflow scenario Glen Canyon Dam will release 14,370 MCM (I 1.650 MAF),

December I, 1999

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