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measurements, which bracket the bankfull discharge. Therefore, the results of the SL model provided a <br />high level of accuracy. The 1998 data was also used to re-calibrate the model. HEC-RAS model results <br />are presented in the technical report. The river cross sections were also re-surveyed in 1998 to monitor <br />any channel morphology changes that can shift stage/discharge relationships up to one foot or even more <br />over the course of time. Cross section data are also included in the technical report. <br />Gunnison River <br />For the Dad's Flat site, aHEC-RAS model was developed to estimate flood stage predictions. The three <br />sets of measured water surface elevations were used to calibrate the model. Results of the modeling and <br />the raw data are included in the technical report. <br />Colorado River <br />The HEC-RAS model for the BO/BR site was originally calibrated in 1997. It was re-calibrated after runoff <br />season 1998 using the additional stage data collected in the 1998 runoff season. The results of the <br />original model proved to be accurate based on the measured water surface elevations. Therefore, the <br />model was not modified. The full results can be found in the technical report. <br />Determination of Current Flooding Discharges <br />Green River <br />One objective of this investigation was to determine flooding discharges for the reaches adjacent to the <br />bottomlands being studied. The following discussion refers to the current flooding discharges, or pre- <br />• levee removal conditions. Top of bank elevations were recorded for each river cross section to determine <br />bankfull discharges, and topographic shots were taken to determine the lowest flooding elevation at each <br />site. In some cases, the river may be at bankfull discharge, but the flood stage is still not high enough to <br />connect to the bottomland. Current flooding discharges are listed in Table 3a. The stage/discharge <br />curves were used to determine the discharges of interest at the SR site and the HEC-RAS model was <br />used for the discharge predictions at the other sites. <br />Gunnison River <br />The existing flooding discharges for the BC and Dad's Flat sites are listed in Table 3b with the <br />corresponding return periods and flood elevations. <br />Colorado River <br />The existing flooding discharges for the B0/BR ponds are listed in Table 3c. <br />• <br />3-3 <br />