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<br />3.0 RESULTS AND DISCUSSION <br />3.1 Chemical and Physical Characteristics <br />Selected chemical and physical characteristics measured at three <br />stations in the Williams Fork River are presented is Table 1. Based on <br />parameters measured or observed, the portion of the river appeared to be <br />suitable habitat for aquatic organisms. The only characteristic which <br />may be limiting at times is the amount of sediment deposited on the rock <br />~I <br />• <br />surfaces. <br />General conditions in the river are summarized below. Dissolved <br />oxygen levels were near saturation on all sample dates. The river was <br />slightly alkaline oa all dates with pH values ranging between 7.2 and <br />7.5. As is characteristic of streams in the Yampa River drainage <br />(Carlson et al. 1979), conductivity (dissolved salts) values increased <br />during low water periods; minimum values (39-41 Nmho) occurred is the <br />spring, while maxima (725-730 Nmho) were observed in November. Turbidity <br />measurements did not appear Co be reflective of conditions is the river. <br />Values were relatively low (less than 20 NTU's) throughout the survey. <br />!laxima which were observed in the spring (12-19 NTU's) were considerably <br />lower than values reported at stations in the Yampa River (Carlson et al. 1979). <br />It is possible that the turbidimeter was not operating properly. <br />Physical characteristics were similar to large mountain streams is <br />western Colorado. Bottom substrates were comprised predominantly of <br />gravel, sand, and cobble at all locations. The only notable difference <br />between the three stations was that less cobble occurred at Station I. <br />During low water periods considerable amounts of silt and detritus <br />covered the rock surfaces both above and below the silo. <br />3.2 Benthic Hacroinvertebrates <br />A total of 56 macroiavertebrate taxa was collected by Surber sampler <br />from the Williams Fork River is 1980 (Table 2). Thirty-five rasa were <br />found at Station '3 during September, which was the highest number of <br />rasa collected at any of the stations throughout the year. The lowest <br />number of rasa was 14 which occurred at Stations 1 and 3 is Juae. <br />Total mean densities exhibited considerable variation between the <br />four sample periods (Tables 3, 4, and 5). The highest mean density was <br />6 <br />