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

2. Runoff and Reservoir Contents and Releases

In 1995, the unregulated inflow into Lake Powell during the April through
July period totaled 11.7 maf, or approximately 149 percent of the 1906-
1985 average. The computed unregulated discharge at Lees Ferry for the
water year ending September 30, 1995 was 16.3 maf, which is approximate-
ly 139 percent of the 1906-1985 average. The following tabulation lists the
breakdown of discharges in acre-feet in the Upper Colorado River Basin:

Net change in surface storage
Net change in bank storage
Net evaporation
Glen Canyon releases
Paria River discharge
Total unregulated discharge at Lees Ferry

Acre-feet
5,525,000
819,000
669,000
9,285,000
19,000'
16,317,000

Dam releases simulating natural hydrographs that are intended to preserve
the endangered species downstream of specific Colorado River Basin dams
are being tested at several locations in the Upper and Lower Basins. Regula-
tion of the Colorado River has had both positive and negative effects on
aquatic resources. Controlled cool-water releases from dams in the Colorado
River Basin have provided for increased productivity of some aquatic
resources and the development of significant sport fisheries. However, the
same releases could be detrimental to endangered and other native species
of fishes.

Consultations with the Service in compliance with Section 7 of the ESA
(Section 7 consultations) on the operation of Glen Canyon Dam on the
Colorado River, the Aspinall Unit on the Gunnison River, Navajo Dam on the
San Juan River and Flaming Gorge on the Green River will continue in 1996.
Studies associated with these consultations will be used to better understand
the flow-related needs of endangered and other native species of fish.
Additionally, interim flow restrictions on releases from Glen Canyon Dam will
continue in water year 1996 while awaiting the issuance of a record of
decision on the Glen Canyon Dam EIS.

The following paragraphs discuss the operations of each of the Colorado
River mainstem reservoirs in water year 1995 and projected operations in
water year 1996.

1 The data for the flow of the Paria River is preliminary and subject to change.

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