WSP07506

• File Number: 822.600.10
• Description: Colorado River Annual Operating Plan - Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/1998
• Author: USDOI/BOR
• Title: Annual Operating Plan
• Water Supply Pro - Doc Type: Annual Report

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Lower Basin Reservoirs

Water shall be released or pumped from Lake Mead to meet the following requirements:

(a) 1944 Mexican Water Treaty obligations;
(b) Reasonable beneficial consumptive use requirements of mainstream users in
the Lower Division States;
(c) Net river losses;
(d) Net reservoir losses;
(e) Regulatory wastes.

The Operating Criteria provide that after the commencement of delivery of mainstream water
by means of the CAP, the Secretary of the Interior will determine the extent to which the
reasonable beneficial consumptive use requirements of mainstream users are met in the Lower
Division States. The reasonable beneficial consumptive use requirements are met depending on
whether a normal, surplus, or shortage condition has been determined. The normal condition
is defined as annual pumping and release from Lake Mead sufficient to satisfY 9,251 MCM
(7.500 MAF) of consumptive use in accordance with Article III(3)(a) of the Operating Criteria
and Article II(B)(1) of the U.S. Supreme Court decree in Arizona v. California. The surplus
condition is defined as annual pumping and release from Lake Mead sufficient to satisfY in
excess of9,251 MCM (7.500 MAF) of consumptive use in accordance with Article III(3)(b) of
the Operating Criteria and Article II(B)(2) of the U.S. Supreme Court decree in Arizona v.
California.

The current water supply conditions forecast mandatory flood control releases that are projected
to be above downstream requirements in January through March of 1998. Using a most probable
inflow forecast for 1998, flood control releases are also projected in January, February, and
March of 1999. Therefore, taking into account (1) the existing water storage conditions in the
basin, (2) the most probable near-term water supply conditions in the basin, and (3) that the
beneficial consumptive use requirements of Colorado River mainstream users in the Lower
Division States are expected to be more than 9,250 MCM (7.5 MAF), the surplus condition is
the criterion governing the operation of Lake Mead for calendar year 1998 in accordance with
Article III(3)(b) of the Operating Criteria and Article II(B)(2) of the decree in Arizona v.
California. While there still is no agreed upon long term strategy for the determination of
surplus conditions, the making of this determination, based on flood control and spill avoidance
considerations, does not preclude the Secretary from adopting other determination criteria in
future years.

Nothing in the decree in Arizona v. California prohibits the Secretary of the Interior from
releasing water apportioned, but unused, irt any Lower Division State for that year for
consumptive use in any other Lower Division Stat~. No rights to the recurrent use of such water
accrue by reason of the use of such water. In light of this provision and in accordance with
Article II(B)(6) of the decree, any Lower Division State will be allowed to utilize water
apportioned to, but unused by, another Lower Division State in calendar year 1998.

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