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~ was calibrated using the standard IFG4 computational procedure. This procedure regresses empirical velocity and WSL data to measured flows and then simulates unmeasured velocities and WSE's at other flows based on these regressions. Deck B was calibrated using the WSEI4S/IFG4 combination where the water surface elevations are calculated in the WSEI4S program (using 3 stage-discharge data sets) and added to the IFG4 data decks on water surface elevation cards. Three additional decks (C,D, and E), retained the 3 stage- discharge measurements, but only one set of velocity versus discharge measurements for a single flow, and were calibrated with the WSEI4S/IFG4 combination. Deck C retained the high flow measured, D the medium flow, and E the low flow. These three decks were used to evaluate the relative calibration range of a one-flow (i.e., one set of velocity distribution measurements for each transect) IFG4 data deck. For additional detailed information on software applications, calibration techniques, and program capabilities, the reader is referred to Milhous et al. 1989. The results of the calibration tests are presented in Table 2. Data decks A and B, which maintained all three velocity measurements, are given a "good" rating with all VAF's between 0.9 and 1.1. Data decks C, D, and E, are all rated "poor" with VAF's as low as 0.27 and as high as 3.97. It is apparent that the three-flow IFG data decks are superior, with little difference between deck A and B. For the one-flow data decks a "good" or "fair" rating is limited to the actual flow measured and calibrated (Table 4). For this analysis, the IFG4 program was used with three sets of velocity and water surface elevation measurements at every transect. The results of the calibration of the Spawning Bar study site, transects 1 through 5, right and left, using the three flow IFG4 program are given in Table 3. Both data decks are assigned a "good" rating for velocity simulation, with VAF's between 0.90 and 1.25, and 0.65 and 1.01, respectively, for the right and left transects. In addition, the velocity prediction errors and percent ratings are provided in Table 4. The velocities calibrated by the program are within an acceptable range for extrapolation 80 percent of the time. ~JA Predictions The primary output of PHABSIM is a predictive index of usable microhabitat called weighted usable area (WUA). The calibrated data decks for transects 6 through 8, and 1 through 5 left, and right, were run through the HABTAT4 program to develop WUA versus discharge relationships for Colorado squawfish (CS) adult life stages and spawning deposition. It is implied from the model output (Table 5) that WUA decreases with an increase in flow for available adult habitat. At the lowest flow simulated, 200 cfs, adult habitat is maximized. When compared to the historic flow of record from 1922 through 1986 (Attachment 2), 200 cfs is exceeded 100 percent of the time in June, 96.9 percent of the time in July, 83.1 percent of the time in August, and 58.5 percent of the time in September. The WUA prediction for spawning/deposition habitat peaks at 2000 cfs, with a gradual decline below 1000 and above 5000 cfs. Only 17 percent of data used for construction of the velocity curve for adult CS was collected in run or riffle habitat, with 58 percent collected in pools, and 18 percent collected from eddies. The resultant velocity curve has a habitat suitability index of 1.0 at zero velocity, drops to 0.1 at around 1.7 k v