9416

• UCREFRP Catalog Number: 9416
• Author: U.S. Department of the Interior.
• Title: Annual Operating Plan for Colorado River Reservoirs 1997.
• USFW Year: 1997.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

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Navajo Reservoir

The April through July unregulated inflow into Navajo Reservoir in water year 1996 was
295 MCM (.239 MAP) or 35 percent of average. Water year 1996 unregulated inflow was
504 MCM (.409 MAP) or 42 percent of average. Navajo Reservoir did not fill in 1996. .

Section 7 consultation with the Fish and WlIdlife Service on the ope.ration of Navajo Dam
continued in 1996. Water: year 1996 was the sixth year ofa seven-year study to evaluate
alternative operations of Navajo Reservoir to benefit endangered fish. In JanU8I)' 1996 a .
two-week test release of250 cfs was made from Navajo Dam to ascertain potential impacts
to aquatic resources inunediately below Navajo Dam. In an attempt to monitor the effects of .
a low runoff year on the San Juan River, spring operations of Navajo were restricted and.
releases of up to 70 ems (2500 cfs) were made during June after the peak flows of the
Animas River had passed. This resulted in peak flows of 113 cms (4.000 cfs) at Bluff: U~. .
After the completion of the large spring releases, releases were gradually reduced to
approximately 17 ems (600 cfs) for the remainder of the year.

In 1997, Navajo Reservoir is expected to nearly fill except under the probable minimum
inflow scenario. As a follow up to the 1996 low flow test, an extended release during
November through FebIU8I)' of water year 1997 will be made to achieve floWs of not less
than 575 cfs at Shiprock, New Mexico, but resulting in flows of not less than 300cfs
inunediately below Navajo Dam. Large releases will likely be made in May and June in
order to improve the habitat and provide better spawning conditions for endangered fish in
the San Juan River. Releases from the reservoir likely will be held near 17 ems (600 cfs)
through the remainder of the year.

Lake Powell

The April through July unregulated inflow into Lake Powell in water year 1996 was 9,004
MCM (7.3 MAP) or 94 percent of average. Water year 1996 unregulated inflow was
13,541 MCM (10.978 MAP) or 95 percent of average. Lake Powell ended the water year
19 feet from full.

During March and April 1996, a test of the BeachlHabitat Building Flow was conducted
from Glen Canyon Dam. The test consisted of peak releases of 45,000 cfs which lasted 7
da~ preceded and followed by 4-day periods oflow steady flows to allow photographic
mapping and monitoring of the canyon resources. While scientific understanding of the
results of this test are not yet complete, data collected to date indicates that the test
accomplished the goals of rebuilding sandbar deposits and refonning eddy backwaters.

This test was implemented following discussions between the Department of the Interior, the
Basin States, and key scientists and researchers which resulted in a long tenn agreement for
managing spills from Glen Canyon Dam. This agreement provides for the use of reservoir
releases in excess of powerplant capacity required for dam safety purposes during high .

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