8173

• UCREFRP Catalog Number: 8173
• Author: Gido, K. B. and D. L. Propst.
• Title: Habitat Use and Association of Native and Nonnative Fish in the San Juan River, New Mexico and Utah.
• USFW Year: n.d.
• USFW - Doc Type: \
• Copyright Material: NO

San Juan River secondary channels, and 2) characterize the degree

of overlap in habitat use by native and nonnative species.

MATERIALS AND METHODS

Study area.-The San Juan River is a major tributary of the
Colorado River and drains 99,200 km2 in Colorado, Utah, Arizona,
and New Mexico (Carlson and Carlson 1982). A detailed
description of the study reach and individual sites is provided
in Gido et al. (in press). Routine operation of Navajo Dam
provides water for agriculture, municipalities, and industry.
This management typically reduces the natural variability of the
river's flow regime by diminishing flows during spring runoff and
elevating base flows during late summer, autumn, and winter
(historic low-flow periods). Reservoir releases during snow-melt
(late spring) and flow from unimpounded tributaries, however,
maintained a quasi-natural pattern of elevated spring flows
followed by low summer through winter flows during our study.
We selected study sites to encompass all primary habitats
(riffle, pool, and run) in the middle or lower portion of four
secondary channels; study site length ranged from 115 to 300 m.
The secondary channels were located between Shiprock, New Mexico
and Bluff, Utah (Figure 1) at river kilometers 140.6, 207.4, F~
216.6, and 226.7 (sites 1 through 4, respectively; Piute Farms
Marina, UT = river kilometer 0.0). Lengths of these channels
were 2.9, 0.9, 3.4, 2.2 km, respectively.

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