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<br />in appendix A. A copy of the flood flow frequency analysis com- <br /> <br /> <br />puter printout, which includes all data and computations for <br /> <br /> <br />each stream gauging station, is included in Appendix B. The re- <br /> <br /> <br />sults of regression analysis for regional curves of selected re- <br /> <br /> <br />currence intervals are shown in Figures 9 and 10 for the Animas <br /> <br /> <br />and Upper San Juan River Basins, respectively. <br /> <br />Peak discharges used for hydraulic computations in the study areas <br /> <br /> <br />were generally determined according to: (1) previous studies; (2) <br /> <br /> <br />regional curves; and (3) weighted discharges between regional curve <br /> <br /> <br />and station statistics. Peak discharges from previous studies were <br /> <br /> <br />used if they are close to the values determined from the regional <br /> <br /> <br />curves established in this study. Sacramento District Corps of <br /> <br /> <br />Engineers has completed a flood hazard information report for Ani- <br /> <br /> <br />mas River, Junction Creek and Dry Gluch Creek in the vicinity of <br /> <br /> <br />Durango (Reference 3) and a flood hazard information report for <br /> <br /> <br />Vallecito Creek (Reference 4). Soil Conservation Service has com- <br /> <br /> <br />pleted a flood hazard study for San Juan River and McCabe Creek in <br /> <br /> <br />the vicinity of pagosa ~prings (Reference 11). Peak discharges <br /> <br /> <br />in these three reports were used in this flood insurance study. <br /> <br />Peak discharges from regional curves were used in reaches where <br /> <br /> <br />no gauging station exists. Weighted discharges were used in <br /> <br /> <br />reaches where qauqing station exists. <br /> <br />In the areas of Bayfield and Ignacio where the flow discharges <br /> <br /> <br />were affected by the regulation of the Vallecito Reservoir, the <br /> <br /> <br />streamflow record at Ignacio after reservoir construction and <br /> <br /> <br />reservoir operation record (Reference 2) were analyzed to obtain <br /> <br />-19- <br />