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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4. Power Schedulinq and Purchases for March 1994

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March water releases from Glen Canyon totaled 607,000 AF. The
weekday generation pattern was pre-scheduled at approximately
6,500 cfs (251 MW) during offpeak hours ramping up to a maximum
of 12,500 cfs (472 MW) during onpeak hours, staying within the
daily maximum fluctuation restriction of 6,000 cfs (232 MW) per
day. Weekend releases were adjusted downward to follow reduced
weekend loads.

March was a warm month, reflecting a stable economy energy
market, with onpeak non-firm energy prices hovering around $22-
23/MWh. There were no events requiring a scheduling adjustment
to Glen Canyon generation. The diversion tunnel was opened in
March which increased generation capability from the Aspinall
units.

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C. Future Schedulinq Concerns for May-September 1994

Coordination of special releases from Flaming Gorge and the Aspinall
units are expected to be difficult to schedule for the Montrose
Power Control staff. Due to low snowpack conditions, the spring
runoff peak is expected to arrive 3 weeks earlier than projected.
This has required Montrose to make adjustments to their non-firm
energy purchase plans.

It is anticipated that Bonneville Power Administration (BPA) will
begin its fish release program, from May through July, delivering a
surplus of low cost energy to the market. Western has contracted
for an allotment of this low cost energy to help alleviate the
reductions expected in power generation from the special releases.

A future concern of Montrose is the combined effect of the scheduled
spike release from Glen Canyon and the ongoing studies at Flaming
Gorge and the Aspinall units that will take place in April of
WY 1995.

IV. ANALYSIS OF RAMPING EVENTS

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A study was made to analyze hourly release rates which appeared to
deviate from interim flow criteria. Operational records and logs kept
during the study period, December 1, 1993, through March 31, 1994 were
reviewed.

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The operational records and logs are contained within the packet Glen
Canyon Dam Interim Flows--Glen Canyon Power Plant Operations, for
December 1993 through March 1994 and provide specific explanations for
each ramping event.

Each page within the packet contains: (1) a strip chart of real-time
Glen Canyon Dam operations during the ramping event, (2) a graph of the
USGS Lee's Ferry Gauge showing river elevation during the ramping event,
(3) a graph of hourly integrated Glen Canyon Dam generation during the
ramping event, and (4) a brief written explanation of the ramping event.

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