7041

• UCREFRP Catalog Number: 7041
• Author: Upper Colorado River Commission.
• Title: Forty-Third Annual Report of the Upper Colorado River Commission
• USFW Year: 1991.
• USFW - Doc Type: Colorado River Storage Project and Participating Projects.
• Copyright Material: NO

completed in March of 1991. The study will develop an interactive
computer model to be used by water managers and planners to forecast
changing municipal and industrial water demands, to evaluate water
conservation implementation strategies and to develop drought contin-
gency plans. The model wiIl be a critical element in developing long-term
forecasts and prioritizing future water resource strategies involving system
optimization and water conservation options and impacts. It wiIl also
assist in evaluating the short-term options necessary to better operate the
existing urban infrastructure.

H. RESERVOIR OPERATIONS

Water year 1991 marked the fifth consecutive year of below normal
flow in the Colorado River Basin. Although basin wide precipitation
during 1991 was over 95 percent of normal, runoff into Lake PoweIl was
only 60 percent of normal. This illustrates the effect that the previous
years ofIow precipitation have had on the basin. Even though inflow on
the Colorado River was below normal during water year 1991, there has
been an improvement in the condition of the basin above Lake PoweIl.
This is demonstrated by the fact that most of the reservoirs located
upstream from Lake PoweIl nearly fiIled during the year and the Palmer
drought index improved from a severe drought to a moderate drought.

During water year 1991, the drawdown of the eolorado River system
reservoirs that began in 1988 continued. An additional 1.7 miIIion acre-
feet was lost from storage in the entire eolorado River storage system
during 1991. The October 1, 1991 system vacant space was about 17.4.
This large vacant space is a result of the five lowest successive years of
inflow into Lake PoweIl on record (1987 through 1991). During this
drawdown period, objective deliveries of water have been maintained in
accordance with the "eriteria for Coordinated Long- Range Operation of
Colorado River Reservoirs" (Operating eriteria).

1. ANNUAL OPERATING PLAN DEVELOPMENT

On October 23, 1990, Secretary of the Interior Manuel Lujan, Jr.
transmitted letters approving an Annual Operating Plan for water year
1991. The Operating Plan was developed through the cooperation of
representatives of the seven Basin States, Reclamation, W AP A and other
agencies.

The Annual Operating Plan was developed with "appropriate consid-

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