7780

• UCREFRP Catalog Number: 7780
• Author: Brooks, J. E., et al.
• Title: San Juan River Seven Year Research Program Summary Report 1992.
• USFW Year: 1992.
• USFW - Doc Type: \
• Copyright Material: NO

consultation period was extended for the length of the research
period (7 years) so as to incorporate findings into the Biological
Opinion. Similarly, formal consultation was requested by BIA for
the last three blocks of NIIP (9-11), with an extension of the
consultation period to coincide with the length of the research
effort .
Specific requirements were outlined in the Reasonable and Prudent
Alternatives formulated for the jeopardy opinions for Animas-La
Plata and NIIP (Blocks 1-8). In addition, Reclamation agreed to
implement a seven year research program for the endangered fishes
of the San Juan River Basin to gather information on the effects of
modifying operations at Navajo Dam.. Development of a long term
Recovery Program with representation from State, Federal, Tribal
and Private interests was also initiated concurrently with the
Research Program.
STUDY AREA - The San Juan River is a major tributary of the
Colorado River in the upper basin of the Colorado River drainage.
The river arises in the mountains of southwestern Colorado and
flows through northwestern New Mexico and southeastern Utah before
entering Lake Powell at the Colorado River confluence (Figure 1).
In Colorado and northern New Mexico, the river passes through
rugged terrain, exhibits relatively high gradient, with the flow
generally restricted to a single channel. An approximate 30 River
Mile (RM) reach of this section is inundated by Navajo reservoir.
Tributary streams to this reach are the Los Pinos, Navajo, and
Piedra rivers.
Below Navajo Dam, the gradient flattens considerably and the river
begins to meander. From Navajo Dam to Fruitland the gradient
remains moderately low, with some braiding, usually limited to one
or two channels with islands. Beginning at about Fruitland,
channel braiding increases. The largest tributary stream to the
San Juan River, the Animas River, is confluent at Farmington, New
Mexico. The La Plata and Mancos rivers also enter the San Juan
River in this reach.
Braiding between Four Corners and Aneth is slightly reduced and the
gradient continues to decrease. From Aneth to just below Bluff
braiding continues to be moderate and the slope remains relatively
constant at its lowest average slope until reaching the San Juan
arm of Lake Powell. McElmo and Montezuma creeks enter the San Juan
River downstream of Aneth.
About 10 RM below Bluff, the river enters a canyon-bounded reach.
The slope increases to about the river gradient near Shiprock and
the river becomes a single channel, before entering Lake Powell.
Prior to construction of Lake Powell, there was another low
gradient, braided channel reach beginning at the now-inundated
confluence with the Colorado River and stretching upstream for
about 60 RM. Recent declines in surface elevation of Lake Powell
2