BOARD00038 ‎(2)‎

• Board Meeting Date: 9/20/2006
• Description: WSP Section - San Juan River Recovery Implementation Program Document Revisions
• Board Meetings - Doc Type: Memo

Flow Recommendations .

In May 1999, the Program's Biology Committee made recommendations as to specific flow
regimes within the reaches of critical habitat in the San Juan River that the committee believed
would provide for the recovery of the populations of the two endangered fish species in the river.
The flow recommendations consisted of: (1) flow statistics for the San Juan River at Four
Corners for spring snowmelt period peak flow rates, durations and recurrence intervals to provide
for creation and maintenance of spawning and rearing habitats for endangered fish; and (2) target
base flows in the San Juan River for the summer, fall and winter months, as measured by a
combination of gages at Farmington, Shiprock, Four Corners and Bluff, to provide low-velocity
habitats for rearing endangered fishes. The flow recommendations were adopted by the
Program's Coordination Committee and have been implemented by modifying operations
decision criteria for Navajo Dam to provide sufficient releases of water at times, quantities and
durations necessary to meet them while maintaining the authorized purposes of the Navajo Unit.

The flow recommendations are not sacrosanct or inviolate, and are subject to change through
adaptive management as new information on habitat and biological response to flows is obtained
from the Program's long-term monitoring activities. Also, the flow recommendations may be
relaxed during periods of extreme drought, in which insufficient flows are available to fully meet
endangered fish flow demands and water user demands, without impairing the survival of
existing populations of endangered fish species in the San Juan River. In response to drought in
the early 2000s, agreements in 2003-2006 were made by water users on the San Juan River, and
were accepted by the Bureau of Reclamation, the New Mexico State Engineer, and concurred in
by the Fish and Wildlife Service, for the administration of diversions from the river and for .
Navajo Reservoir operations that provided for a sharing of limited water supplies among water
users and fish habitat flows in the event of anticipated shortages.

Navajo Dam and Reservoir Operation

The Colorado River Storage Project (CRSP) Act authorized as storage units Lake Powell on the
mainstem of the Colorado River, the Aspinall Unit on the Gunnison River, Flaming Gorge
Reservoir on the Green River, and Navajo Reservoir on the San Juan River. The Bureau of
Reclamation operates and maintains all four dam and reservoir units of the CRSP. Navajo Dam is
located on the San Juan River in New Mexico just below the confluence with the Los Pinos
River, and the reservoir area lies predominantly within New Mexico with a small portion of the
reservoir area lying within Colorado. The operation of Navajo Reservoir is subject to the terms of
the Upper Colorado River Basin Compact, the Colorado River Storage Project Act, and the Act
of June 13, 1962, authorizing the San Juan-Chama and Navajo Indian Irrigation projects. The
authorized purposes of the CRSP are: regulating the flow of the Colorado River, storing water for
beneficial consumptive use, making it possible for the States of the Upper Basin to utilize,
consistently with the provisions of the Colorado River Compact, the apportionments made to and
among them in the Colorado River Compact and the Upper Colorado River Basin Compact,
respectively, providing for the reclamation of arid and semiarid land, for the control of floods,
and for the generation of hydroelectric power, as an incident of the foregoing purposes.

Construction of the four CRSP units was critical to the development of the water resources of the
Upper Basin; however, natural riverine habitats were altered due to the variation of natural flow
regimes, water quality and water temperatures caused by operation of the CRSP units. A
reevaluation of Navajo Reservoir operations began when Reclamation requested formal .

14