WSP02900

• File Number: 8220.101.08
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 10/1/1994
• Author: Western Area Power A
• Title: Glen Canyon Dam Interim Operations - Estimated Net Expense - April 1994 through Sepyember 1994
• Water Supply Pro - Doc Type: Report/Study

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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 pre-schedules. These restrictions
have required Western to request customer pre-scheduling 3 days in
advance in order to match firm loads to available project resources
and substitute purchases for any hourly deficits. Hourly changes to
pre-schedules 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 SLCA/IP resources to the
contractors' alternate resources. A majority of these other
resources are thermal and have higher costs associated with their
use,

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B. Power Scheduling and Real-Time Operations

1. Power Schedulinq and Purchases for April 1994

April water releases from Glen Canyon totaled 610,000 acre feet
(AF). The weekday generation pattern was pre-scheduled at
approximately 7,200 cfs (257 MW) during off-peak hours ramping up
to a maximum of 13,200 cfs (472 MW) during on-peak hours for a
majority of the month. this stayed within the daily maximum
fluctuation restriction of 6,000 cfs per day (215 MW)' Weekend
releases were adjusted downward to follow reduced weekend loads.

Firm purchase requirements in April were generally supplied
through long-term purchase agreements.

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2. Power Schedulinq and Purchases for Mav 1994

May water releases from Glen Canyon totaled 599,000 AF. The
weekday generation pattern was pre-scheduled at approximately
7,200 cfs (263 MW) during off-peak hours ramping up to a maximum
of 13,200 cfs (4B2 MW) during on-peak hours for a majority of the
month. This stayed within the daily fluctuation restriction of
6,000 cfs per day (219 MW). Weekend releases were adjusted
downward to follow reduced weekend loads.

On May 7 spring runoff increased releases from the Aspinall Unit.
The U.S. Fish and Wildlife Service (FWS) requested a 3-day
4,000 cfs release from the Aspinall Unit to enhance flows on the
Gunnison River for endangered fish.

3. Power Schedulinq and Purchases for June 1994

June water releases from Glen Canyon totaled 624,000 AF. The
weekday generation pattern was' pre-scheduled at approximately

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