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12 large island into a major and minor channel. The smaller channel was about 4 m wide during the September sampling. Very shallow riffles and moderately deep pools (maximum depth 1 m) in this side channel were sampled. Small boulders (to 1 ft [1/3 m] diameter) and silt made up the bottom substrate of both pools and riffles. Station 4 - Ignatio Upstream (Figure 7): The valley bottom at this site was narrow but with a substantial riparian zone where cottonwood, sagebrush, and salt cedar were dominant. An island split the river into a small channel (maximum width 3 m) and a large channel (maximum width 30 m). A riffle section with a clean, small rubble and gravel substrate was sampled in the large channel. In the small channel, which was also sampled, there was little flow and the bottom was heavily silted. Station 5 - Ignatio Bridge (Figure 8): This site was only 0.5 mi (0.8 km) downstream from Station 7 but represented very different riverine habitat. There was an extensive network of small channels, sandbars and backwater pools both connected to and separated from the main channel. Each of these pools was sampled as well as riffle, run, and pool habitat on the main channel. Station 6 - Walkable Wash (Figure 9): The river meandered through a relatively broad, fiat valley bottom. The riparian zone was covered with cottonwoods, willows, and grasses. Sampling was conducted in a braided section of the river on the smaller channels. Pools bordered by logs and other debris, and short riffles with gravel and sand substrate were sampled over a 1000' (300 m) section. Station 7 - Old Cabin Site (Figure 9): This station was 0.5 mi (0.8 km) downstream from Station 6. Habitat at this station was similar to that at Station 6, except that more backwater areas and isolated pools were present where the river curved around a large gravel bar devoid of vegetation.