7901

• UCREFRP Catalog Number: 7901
• Author: Upper Colorado River Commission.
• Title: Forty-Seventh Annual Report of the Upper Colorado River Commission.
• USFW Year: 1995.
• USFW - Doc Type: Salt Lake City, Utah.
• Copyright Material: NO

resulted in flows of over 12,000 cfs at Bluff, Utah. After the completion of
the large spring releases. flows were reduced to approximately 800 cfs for
the remainder of the year.

The operation of Navajo Dam has been impacted through the Service's
Biological Opinion on tne Animas-La Plata Project. In addition to requiring
high spring releases to mimic a natural hydrograph, the updated 1996 Biologi-
cal Opinion required low winter releases to store water in Navajo Reservoir
for the following spring release.

Historically. a flow of at least 500 cfs has been attempted to be released
to support the quality trout fishery immediately below the dam. The modeling
associated with the Animas-La Plata Biological Opinion revealed that in order
to produce large spring releases in nearly all years, the winter flows would
have to be reduced to about 300 cfs. Test releases of this flow were
conducted in January 1996 and will be followed by a 4-month period in the
winter of 1996-1997. Results of the tests will be used to evaluate the
impacts of changing the flow regime below Navajo Dam.

In 1996, Navajo Reservoir is expected to nearly fill except under the
probable minimum inflow scenario. Releases from the reservoir will be held
near 600 cfs through the fall and winter months, and 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. The release
from Navajo will be closely coordinated with all parties interested in the
operation of Navajo Reservoir.

e. Blue Mesa, Morrow Point and Crystal Reservoirs (Aspinall Unit)

In water year 1995, the April through July unregulated runoff into the
Aspinall Unit was 1,605,000 acre-feet, or 230 percent of average. Water
year 1995 unregulated inflow into Blue Mesa was 1,643,000 acre-feet. or
151 percent of average. Water year 1995 powerplant bypasses were
953,000 acre-feet at Crystal, 285,000 acre-feet at Blue Mesa and 187,000
acre-feet at Morrow Point.

Section 7 consultation with the Service on the operation of the Aspinall
Unit continued in 1995. As part of this consultation, a five-year plan was
outlined to study the effect of various release patterns on habitat and
possibly on the reproductive success and reintroduction of endangered fish
in the Gunnison River. Water year 1995 was the fourth year of this 5-year
study and was considered a high-flow scenario.

Additionally, the Aspinall Unit was operated as if the draft contract were
in place among Reclamation, the National Park Service and the State of

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