WSP09978

• File Number: 822.600.10
• Description: Colorado River Annual Operating Plan - Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/1994
• Author: USDOI/BOR
• Title: Annual Operating Plan
• Water Supply Pro - Doc Type: Annual Report

reduced to 5,7 m3fs (200 cfs), Under all but the most adverse inflow scenarios, Blue Mesa
is expected to fill in the summer of 1994 and flows through the Black Canyon of the
Gunnison National Monument are expected to be above the minimum release objective during
the summer months, The filling of the reservoir nex~ year will ensure that reasonable
specific releases required to study the protection and improvement of habitat for endangered
fish can be accommodated. The forecast runoff for the spring of 1994 will be monitored to
achieve these objectives, To protect the blue ribbon trout fishery in the Black Canyon and
maximize recreation potential, releases during 1994 will be planned to minimize large
fluctuations in the daily and monthly flows. These operations to reduce"flow fluctuations
limit the capability of The Colorado River Storage Project Act powerplants to respond to
changes in electrical demand in the region.

Navajo Reservoir

The April through July unregulated inflow into Navajo Reservoir in water year 1993 was
1,188 MCM (,963 MAF) or 145 percent of average. Water year 1993 unregulated inflow is
expected to be 1,663 MCM (1.348 MAF) or 141 percent of average. In order to
accommodate the high spring inflow, releases were increased in late February, reached
127,4 m3fs (4,500 cfs) in early March, and were mlrlntained at that level through May 1.
During the first part of May it became apparent that inflow was not going to be as high as
forecast and releases were reduced to 42,5 m3fs (1,500 cfs) until June 2, 1993, when releases
for endangered fish were initiated, Navajo Reservoir nearly filled in July, 1993,

Section 7 consultation with the Fish and Wildlife Service for the operation of Navajo Dam
was continued in 1993, Water year 1993 was the third year of a 7 year study to evaluate
alternative operations of Navajo Reservoir to benefit endangered fish. In accordance with
this 7 year study, spring operations of Navajo were modified in 1993 and large releases of up
to 127.4 m3fs (4,500 cfs) were made during the first part of June to coincide with the peak
flows of the Animas River to study the effect of large spring flows on the habitat
improvement and spawning success of endangered endemic species of fish. Due to this
operation, flows of over 311.5 m3fs (11,000 cfs) were achieved at the confluence of the
Animas River with the San Juan near Farmington,' New Mexico, This flow was less than the
estimated safe channel capacity of 339,8 m3fs (12,000 cfs), so that no major flooding
occurred on the San Juan River. After the completion of the large spring releases, flows
were reduced to approximately 17.0 m3fs (600 cfs). The objective was to maintain a
minimum release of 14,2 m3fs (500 cfs) from the reservoir to meet downstream demands and
to preserve the blue ribbon sport fishery located iinmediately downstream of the reservoir;
The release of 14,2 m3fs (500 cfs) is an objective only and is not a minimum flow
requirement.

In 1994, Navajo Reservoir is expected to nearly fill except under the probable minimum
inflow scenario, Releases from the reservoir will be held near 14,2 m3fs (500 cfs) through
the fall and winter months and large releases will be made in May and June in order to study
measures to improve the habitat and provide better spawning conditions for endangered fish
in the San Juan River. Under the probable minimum inflow scenario, releases of

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