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. . To better represent the underlying distribution, depth and velocity data were subjected to a class optimization procedure before final curves were generated. This optimization procedure combines or 'bins' the data into more optimum cell widths. The number of classes was obtained from the following relationship: m = 1.0 + 3.3 x log (n) . where: m = the number of classes, n = the number of data values (sample size), and . log is the base 10 logarithm (Haan 1977). . The difference between the maximum and mlnlmum values for a partition divided by the calculated number of classes determined cell width. This is the procedure used by the EWS in its instream flow model IFGSTAT. A smoothed curve was generated to fit the optimized histogram for depth c; '" ,,,,\1 and velocity. Depth curves were fitted using a generalized Poisson model )~c ".t\ (Bovee 1986), while velocity curves were generated using an exponential model ~o,rS"'" (Haan 1977). These depth and velocity curves were placed on a scale where maximum utilization was assigned a value of 1.0. . . The dominant and secondary substrate associated with each point measurement were both used to generate the HSI curve. These were placed in classes that combined each of the six substrate types into a total of 36 possible combinations. Of these, only 14 were observed. The substrate data were not optimized, but were represented as histograms in raw data form, since these data did not represent a continuous function. A maximum utilization of 1.0 was assigned to the substrate classification with the highest frequency. . The distribution of habitats (backwaters, runs, pools, etc.) used by radiotagged fish was also presented to show the general habitats where measurements of depth, velocity, and substrate were taken. statistical Tests A series of statistical tests were conducted to examine: . 1. The distribution of depths, velocities and substrates obtained with the 2-hour monitoring design versus samples taken over a full 24 hours. - 2. The relationship between habitat parameters measured at the fi~ with those taken one meter~ or out from this point. . 11 .