WSP01318

• File Number: 8220.101.08
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 5/1/1994
• Author: Western Area Power A
• Title: Glen Canyon Dam Interim Operations - Estimated Net Expense - December 1993 through March 1994
• Water Supply Pro - Doc Type: Report/Study

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significant impact on the daily operation of Western Area Power
Administration's (Western) Upper Colorado Control Area.

The impacts of this change in dam operations have required Western to
implement new scheduling procedures for its customers, develop interim
release gUidelines for real-time operations, purchase higher-priced
energy during onpeak periods, and increase the firm-power rates to its
customers to cover the additional costs.

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The following sections are a review of Power Operations for the
reporting period.

III. SCHEDULING

A. Interim release restrictions have limited Western's ability to
accommodate hourly changes in the preschedules. These restrictions
have required Western to request customer prescheduling 3 days in
advance in order to match firm loads to available project resources
and substitute purchases for any hourly deficits. Hourly changes to
preschedules 'have been restricted by the lack of system flexibility.
The burden to adjust to changes in real-time load has shifted from
the contractors' use of their SLCAjIP resources to the contractors'
alternate resources. A majority of these other resources are
thermal and have higher costs associated with their use.

B. Power Scheduling and Real-Time Operations

1. Power Schedulinq and Purchases for December 1993

December water releases from Glen Canyon totaled 800,000 acre
feet (AF). The weekday generation pattern was pre-scheduled at
approximately 10,000 cfs (390 MW) during offpeak hours ramping up
to a maximum of 17,000 cfs (663 MW) during onpeak hours for a
majority of the month, staying within the daily maximum
fluctuation restriction of 8,000 cfs (273 MW) per day. Weekend
releases were adjusted downward to follow reduced weekend loads.

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December's weather was mild, allowing for consistent allocation
scheduling by SLCAjIP contractors'. Water allocated for December
placed the daily fluctuation restriction at 8,000 cfs (800,000
AF). High test flows at Flaming Gorge and ramping restrictions
(one daily peak limited to 30 MW, up ramp and down ramp) limited
the exposure of the trout population to high fluctuations.
Western's long-term purchase contracts were curtailed for the
first half of the month because of high releases. These
unplanned reductions in purchases resulted in decreased revenue
for utilities that have long-term purchase agreements with
Western.

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2. Power Schedul inq and Purchases for January 1994

January water releases from Glen Canyon totaled 806,000 AF. At
the beginning of the month, generation fluctuated between 10,500
cfs(408 MW) and 18,500 cfs (719 MW). At the end of the month,
generation was pre-scheduled at 9,500 cfs (368 MW), ramping up to

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