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<br />or Class II pools. The primary habitat available to Colorado squawfish at all simulated flows (1-500 <br />cfs) were shallow run habitats. <br /> <br />Combined clusters in Strata 2,3, and 4 <br /> <br />Figure 10 and Appendix 2, Tables 1-5 show habitat composition when all 28 cross sections in <br />strata 2, 3 and 4 are combined. Total river reach represented by the 28 cross sections (5,805 ft) is <br />3.1 % of Strata 2,3 and 4 (35.6 miles). Shallow runs (unusable habitat) are the most common <br />habitats available at flows between one and 500 cfs, <br /> <br />Figure 11, gross habitat versus flow, shows a rapid increase in wetted surface area between one <br />and 100 cfs, but between 100 and 500 cfs surface area increases linearly. Usable surface area <br />increases in a fairly linear relationship with flow between 1 and 250 cfs. The amount of usable area <br />at 200 cfs is only double that of what is projected at 1 cfs. <br /> <br />With only one cfs of flow, the wetted surface area of the river models to be 9,627 ft.'!100 ft. in <br />strata 2 (rm 20.0-45.5), 17,414 ft-'Il 00 ft. in strata 3 (rm 45.5,51.0), and 42,787 ft.'1l 00 ft. in strata <br />4 (nn 51.0-54.0) (Appendix 2, Tables 1-5). <br /> <br />The mean stream width were 10.1 ft. in strata 2 (rm 20-45,5), 15,5 ft. in strata 3 (rm 45.5-51,0). <br />and 40.0 ft. in strata 4 (rm 51.0-54.0) at one cfs, The river maintains width at very low flows in <br />clusters 3 and 4 because of its flat gradient and the low width/depth ratio. <br /> <br />A width/discharge relationship was determined by averaging the widths of each cross section in <br />a sequence for each of the simulated flows. (Mean cross' sectional width is different from the mean <br />stream width as determined by Appendix 2, Tables 1-5). The width/discharge relationship was <br />highly variable for cross sections within a cluster and between clusters. High gradient habitats <br />(riffles) had narrower widths at low flows than low gradient habitats with low width/depth ratios. <br />Cluster 2 (rm 20.0-45.5) had the lowest average cross sectional width at 1 cfs (10.1 ft.) and Cluster <br />3 (rm45.5-5l.0) had the widest average cross section width at 500 cfs at 290 ft. (Figure 12). <br />Between one and 100 cis. stream width increases rapidly with flow, but at flows between 150 and <br />500 cfs the relationship is fairly linear. Mean channel width, grass line to grass line, were found to <br />average about 229 ft. for cluster 2 (rm 20-45.5), 458 ft. For cluster 3 (rm 45.5-51.0), and 306 ft. for <br />cluster 4 (rm 51.0-540), The mean cross section width of strata 2 at 500 cfs was 139 ft. or about <br />61 % of the bankfull width, 298 ft. For cluster 3 or about 65% of the bankfull width, and 227 ft. For <br />cluster 4 or about 74% of bankfull width. <br /> <br />Coefficients of variation for width were highest at the lowest flow (1 cfs) and decreased with <br />increased flow (Figure 13). This is expected since riffle and run widths become more uniform as <br />How increases. The relationship between width C.V. and flow was curvilinear at between one and <br />100 cfs with an intlection point at 40 cfs for cluster 2 (tIn 20-455). 50 cfs for cluster 3 (rm 45.5- <br />51.0), and 60 cis It)r cluster 4 (rm 51.0-54.0) <br /> <br />23 <br />