WSP09160

• File Number: 8220.101.08
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 6/1/1993
• Author: USDOI - BOR
• Title: Glen Canyon Dam - Monitoring of Interim Operating Criteria - June 1993 through November 1993
• Water Supply Pro - Doc Type: Report/Study

Deviations from the ramp rate criteria have occurred periodically, particularly when the
dam is following the power load under system regulation and generally occurs during the
up ramp. Such deviations are allowed under the generator regulation exception criteria.

The estimated net expenses of interim operations are included in Appendix C. Summary
of estimated costs by month is shown in the following tabulation:

Month
June 1993
July 1993
August 1993
September 1993
October 1993
November 1993

Net Expense
$618,118
$680,830
$552,370
$446,771
$387,899
$464,447

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To date, financial exception criteria have not been used.

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INTERIM FLOW MONITORING PROGRAM. RESOURCES AND RESPONSES

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The program focuses on the evaluation of critical resources and ecosystem processes
relative to the interim flow regime to determine natural changes in the ecosystem,
changes as a result of interim flows, and effects on power generation.

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Resource Response. Environmental and cultural resources in the Glen and Grand
Canyon areas have been continuously monitored during the last three months. The
intent of the interim flow monitoring is threefold; (1) to satisfy the interim flow
objectives; (2) to provide additional information for completion of the GCES Phase II
research programs; and (3) to define the baseline for the long-term monitoring program.
The following resource categories were monitored.

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Sediment. The importance and longevity of the sediment
deposits laid down in the January and February 1993 floods from the little Colorado
River continue to be a focus of much of the sediment resource monitoring effort. The
majority of the sediment deposits have been eroded back to the pre-January 1993 levels
with the sediment moving into the adjacent backwaters, return channels and eddies. This
movement of sediment into adjacent areas is providing the "bank account" of sediment
that is the focus of the proposed 1995 flood release experiment.

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There has been no high runoffs or severe winter storms this
year in the little Colorado or Paria River drainages. With the low snowpack in the
Little Colorado River basin a large runoff is not anticipated. Glen Canyon Dam releases
are set for a low 8.23 maf year release so we do not anticipate that the bank account of
sediment in the main channel will be moving prior' to the experimental flood next spring.

GCES is planning our annual Memorial Day low flow aerial
photography run in the Grand Canyon again this year. The photographs, collected at a
steady flow of 8,000 cfs have provided valuable pictures of what the system looks like.
We are hoping that we have clear weather and a base flow situation in the Little