WSP03790

• File Number: 8220.101.13
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 10/1/1998
• Author: Secretary of Inter
• Title: Report to Congress: Operations of the Glen canyon Dam Pursuant to the Grand Canyon Protection Act of 1992 ‎(Water Years 1997 and 1998)‎
• Water Supply Pro - Doc Type: Annual Report

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from Lee Ferry,

The floods brought an unusually large amount of sediment from the Paria River drainage into
the Colorado River, estimated at over 2 million cubic meters in volume. Researchers felt that
this sediment would be quickly transported downstream and desired to carry out some type of
high release from the dam in order to move the sediment from the main channel into eddies
and channel margins where less sediment would be transported downstream. Since there
were no hydrologic or dam safety reasons to conduct another beach/habitat-building flow as
was the case in March 1996, a release at powerplant capacity was scheduled as a type of test
of the habitat maintenance flow described in the GCDEIS.

On November 4-5, 1997, a 48-hour release at powerplant capacity (30,600 cfs at the time)
was made. The average daily releases before and after the release were about 21,000 cfs;
thus, the test flow increased the river discharge by about 10,000 cfs, a 45 percent increase.
The river stage increased between about 1,5 feet to 3 feet depending on the location in the
Grand Canyon. The preliminary impacts of the high flow are described in a memorandum
from the GCMRC (see Appendix F).

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ADAPTIVE MANAGEMENT PROGRAM

Section 1805(a) of the GCPA directs the Secretary to:

. . . establish and implement long-term monitoring programs and activities that
will ensure that Glen Canyon Dam is operated in a manner consistent with that of
section 1802.

Section 1805(b) of the CGPA states that:

Long-term monitoring of Glen Canyon Dam shall include any necessary research
and studies to determine the effect of the Secretary's actions under section 1804( c)
on the natural, recreational, and cultural resources of Grand Canyon National Park
and Glen Canyon National Recreation Area.

One of the key elements specified in the GCDEIS and ROD is an "Adaptive Management
Program." The AMP provides a process for incorporating science and recommendations
from a diverse group of stakeholders in the evaluation and management of future dam
operations. The AMP calls for the continued interaction of managers and scientists to
monitor the effects of current dam operations on the Colorado River ecosystem, and to
conduct research on alternative dam operating criteria that may be necessary to ensure
protection of resources and improve natural processes.

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The AMP, schematically characterized in Figure I on page 6, identifies the following entities