WSP06394

• File Number: 8283.100
• Description: Colorado River Computer Models - Colorado River Simulation System
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 6/20/1986
• Author: Unknown
• Title: Appendix A - 1986 Lower Colorado River Simulation Studies
• Water Supply Pro - Doc Type: Report/Study

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Surplus Strategy (All Three Studies)

The model delivers surplus water to California {via The Metropolitan Water
District of Southern California (Metropolitan) and Arizona (via CAP),
beginning in January, for a full calendar year if the previous
end-of-December vacant reservoir storage space was less than 7.35 maf
(2 maf in excess of the minimum flood control space required by the
Hoover Dam - Lake Mead flood control regulations).

The amount of surplus water made available was the difference between CAP's
maximum capacity of 3,000 cubic feet per second and its normal delivery
schedule. This,volume of water over the calendar year permitted CAP to
pump at its capacity and Metropolitan (referred to as MWD in summary
information) to increase its diversion by the same surplus volume that is
diverted by CAP. Additionally, CAP and Metropolitan were assumed to pump
to their maximum capacity those volumes of water, in excess of downstream
water user requirements that result from Hoover Dam flood control releases.
The model considered Metropolitan capable of pumping surplus water
beginning in 1986 and CAP beginning in 1992.

Shortage Strategy (All Three ~tudies)

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The simulation of water shortage conditions in the Lower Basin was governed
by the assumption that should the Lake Mead elevation' fall below 1095 feet,
at the end of a calendar year, the subsequent year's diversion by CAP was
limited to 450,000 acre-feet. Beginning in 203Q, when Nevada is scheduled
to begin consuming its full apportionment, Arizona's s~are of the total
wa-ter shortage was 96 percent and born by CAP. Nevada's share of 4 percent
was borne by SNWP.

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Scheduled Consumptive Uses (All Three Studies)

The Upper Colorado River Basin depletion schedule was taken from ,the
September 1984 "Projected Water Supply and Depletions, Upper Colorado River
Basin." It should be noted that while this was the depletion schedule used
for the 1985 CAP water supply study, the depletions estimated for the oil
shale industries and accompanying municipalities and industries have been
reduced in the State of Colorado. Primarily due to _Colorado's reduced
schedule, the resulting Upper Basin depletion schedule used for the current
studies was generally lower than that used in the earlier CAP water supply
study.

The Lower Colorado River Basin depletion schedule,was taken from the
September 1982 "Consumptive Use and Diversions from Mainstream."
Modifications to the September 1982 estimates were made for SNWP and CAP.
In the Lower Colorado River Basin, SNWP depletions were taken from the
October 18. 1983 "State of Nevada, Colorado River Water Budget." CAP's
scheduled diversions were taken from the Arizona Projects Office's
"ASSUMPTIONS FOR ESTIMATED CAP DELIVERY - EARLY YEARS," dated June 1985.
Annual diversion quantities were distributed by months according to a
percentage formula ~hich applies throughout the entire period of study.

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