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al] were measured and weighed. Special care was taken to identify potential catostomid hybrids We identified these based on morphological characteristics of the mouth and body that were intermediate between putative parental types and on intermediate squamation patterns and scale counts in the lateral series (Hubbs and Miller 1953). Smallmouth bass captured in the treatment reach during native fish response evaluation sampling were also removed. Some of those smallmouth bass were also preserved in ethanol to provide specimens for studies of timing and duration of spawning via otolith analysis. Small numbers of voucher specimens of unusual (darters) or difficult to identify taxa (small suckers) were preserved and are housed at the Larval Fish Laboratory, Colorado State University. Stream flow and water temperature data collection and presentation.-Most streamflow data were from the State Highway 40 bridge site near Maybell, CO, (U. S. Geological Survey gauge 09251000), which is near the downstream end of the study area.. Temperature data were collected at that site and at Government bridge (G. Smith, U. S. Fish and Wildlife Service, Denver, Colorado); USGS data were used to supplement Recovery Program information. We characterized flows in a historical period (1979-1999), which starts just after the time intensive sampling began in this area. We used water temperature data collected since 1991 to describe thermal conditions in pre-drought (1991-1999, ] 996 missing) and drought (2000-2005, full 2006 data not yet available) periods. Flow and water temperah~re data from periods prior to 2000 are contrasted with that from drought years 2000 to 2006 to provide a perspective on differences in physical habitat among the periods and that available during fish sampling from 2003 to 2006. Age-0 smallmouth bass age and growth.-In order to gain more information about smallmouth bass ecology in the study area, we undertook some preliminary studies of otolith microincrement structure. We initiated these studies with fish collected in 2005, with an eye towards demonstrating the utility of the technique and possible expansion to other river reaches and years if the technique is successful. Fish were randomly selected from a series of ethanol- preserved samples collected throughout the late summer and early autumn. Fish were measured and otoliths extracted, attached to microscope slides with glue, and polished on one side until increments were visible. Increments were counted via techniques in the published literature 6