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- 17 - FUTURE FLOODS i;: Floods of the same magnitude as those that have occurred in the past can recur in the future, and even larger floods are possible. The discussion of future floods in this report is limited to those designated as the Intermediate Regional and Standard Project Floods. The Standard Project Flood would be larger and occur less frequently than the Intermed- iate Regional Flood. The Standard Project Flood is a rare event, but could reasonably be expected to occur in the future. In addition to determining the Intermediate Regional Flood and the Standard Project Flood, the 10 and 25-year recurrence floods have also been identified at various des- ign points along the Blue River into Dillon Reservoir. Floods larger than the Standard Project Flood are also poss- ible, but the probability of their occurrence becomes increasingly remote. Determination of the runoff for these floods was based on hydrologic computation, which included analysis of avail- able records of past floods and consideration of pertinent meteorologic and physiographic conditions. Snowmelt floods on the river and cloudburst floods in the tributary basins create the more severe flood conditions in the study area. FREQUENCY OF FLOODING The Intermediate Regional Flood is one that could occur about once in 100 years on the average, although it has a one percent probability of being equalled or exceeded during anyone year. The runoff from a Standard Project Flood is that generated by a severe combination of meteorological conditions reasonably characteristic of the hydrologic region excluding extremely rare combinations. It is diffi- cult to assign a frequency to the recurrence of a storm of such magnitude but for purposes of this study can be regarded as having recurrence of about once in 500 years. ~ Leonard Rice Consulting Water Engineers, Inc.