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Summer During summer, flows decline in magnitude from relatively high levels in July to the yearly low in September; water temperatures are at an annual high during July and August. Use of fast runs peaked in July at 26% and then tapered off to 7% in September. Conversely, use of slow runs in- creased during this period: after reaching an annual low in late spring (13%) use steadily increased through summer (26-55%) and peaked during the transitional month of October (61%). Together the two run types accounted for 49-52% of habitats selected during summer. Backwaters were little used during this time (3-7%) and flooded gravel pits were largely unavailable. Shorelines and rapids each accounted for only 04% use. Annual use of riffles was highest during the summer months but use was relatively low compared to other habitat types (3-10%). Squawfish use of eddies also reached a yearly high during summer (9-16%). Pools were used to a significant degree (13-16%); however, like spring use, summer use of pools was low compared to the remainder of the year. March and October Flows and temperatures are low during the transitional months, with temperature somewhat higher during October than during March. Pools and slow runs are primarily selected during these months: pool use accounted for 32% in March and 26% in October; slow runs, 43% in March and 61 % in October. Large backwaters were used 14% of the time in March and 9% in October. Other habitat types were used little or not at all: eddies were used 4-7%; fast runs 04%; riffles, rapids, shorelines were not selected; flooded gravel pits were unavailable. Adult Razorback Sucker Winter Seasonal habitat use patterns are somewhat different for razorback sucker than for Colorado squawfish (Figs. 5 and 6; Appendix Table IV). Other than during the spawning period, individual razorback suckers appear to have very localized home ranges. Though razorback suckers were caught and radio tracked within the 15-mile reach during spring, all radiotelemetry information during the remainder of the year came from the 18-mile reach. Whether some razorback suckers use the 15-mile reach throughout the year is not known. Though data are limited (3-15 observa- tions per month; 1-4 different fish), the pattern appears to include an extended winter period that lasts from November through April. During this time, razorback sucker are primarily located in pools (61 %) and slow runs (24%); they are also occasionally found inhabiting low-velocity eddies (11%) associated with pools. Spring In April or May razorback sucker begin to move in search of spawning sites. Use of pools appears to drop off entirely during May while slow run (36%) and backwater habitat (45%) use increases. Flooded gravel pits become available during June and razorback sucker tend to seek these sites out for either staging or spawning activities. Gravel pits account for 43% of the June observations; 18