WSP00672

• File Number: 822.600.10
• Description: Colorado River Annual Operating Plan - Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/1993
• Author: USDOI/BOR
• Title: Annual Operating Plan
• Water Supply Pro - Doc Type: Annual Report

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12

1993 DETERMINATIONS

The AOP provides guidance regarding reservoir storage and release conditions during the
upcoming year, based upon congressionally mandated and judicially ordered storage, release,
and delivery criteria and determinations. After meeting these requirements, specific
reservoir releases may be modified as forecasted inflows change in response to climate
variability and to provide additional benefits to the projects' multiple purposes.

Upper Basin Reservoirs

The Operating Criteria provide that the annual plan of operation shall include a determination
of the quantity of water considered necessary to be in Upper Basin storage at the end of the
water year. Taking into consideration all relevant factors required by the Operating Criteria,
it has been determined that the active storage in Upper Basin reservoirs forecasted for
September 30, 1993, exceeds the storage required under Section 602(a) of the Colorado
River Basin Project Act (Public Law9()..537) 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 1993.

Section 602(a)(3) of the Colorado River Basin Project Act, Public Law 9()..537, provides for
the storage of Colorado River water in Upper Basin reservoirs, not required to be released
under Articles IlI(c) and IlI(d) of the 1922 Colorado River Compact, to the extent the
Secretary of the Interior, after consultation with the Upper Colorado River Commission and
representatives from the three Lower Division States, and taking into consideration all
relevant factors (including, but not limited to: historic stream flows, the most critical period
of record,' the probabilities of water supply, and estimated future depletions), finds it
necessary to assure deliveries to comply with Articles IlI(c) and IlI(d) of the 1922 Colorado
River Compact, without impairment of annual consumptive use in the Upper Basin. Water
not required to be so stored shall 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 IlI(e) of the Colorado River Compact, but no such
releases shall be made when the active storage in Lake Powell is less than the
active storage in Lake Mead,

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

. to avoid anticipated spills from Lake Powell.

Because Lake Powell's active storage is projected to be less than Lake Mead's active storage
(except for probable maximum inflow), storage equalization provisions will probably not
control the release from Lake Powell. Therefore, the objective shall be to maintain a