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Insurance Study. Maps and flood elevntions will be smended periodically to reflect future changes. 3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish peak discharge- frequency relationships for each flooding source studied by detailed methods affecting the community. A hydrological analysis of flows in Oak Creek was performed for snowmelt and/or rainfall runoff over the basin. There are no active streamflow gage records on Oak Creek. A gage was formerly existent on Oak Creek for only S years (water years 19S3 to 19S7). It was located 4.S miles southwest of the Town of Oak Creek. The length of record of this gage was insufficient to be analyzed and provide meaningful results. The U.S. Soil Conservation Service's (SCS) unit hydrograph procedure (Reference 3) was then employed to determine the lOa-year peak streamflow. Significant parameters used with this method were a lOa-year 24- hour rainfall of 2.8 inches and a SCS curve number of 70. A lOa-year peak flow was computed using the assumed basin parameters and compared with the flow values of other streams in the region (Reference 4). Through this comparison, the lOa-year peak flow was adjusted to reflect the runoff characteristics of the basin. The la-year flood event was assumed to be the result of a snowmelt event. This value was obtained from a regional analysis of streams which had acceptable gage records and similar characteristics_ Peak discharge-drainage area relationships for Oak Creek are shown in Table 1. TABLE 1 - SUMMARY OF DISCHARGES Flooding Source and Location Drainage Area (Sa. Miles) Peak DiSCharge (cfs) la-Year SO-Year lOa-Year SOO-Year Oak Creek At the Town of Oak Creek 22.7 300 * 1,OSO * *No Data Available 3.2 Hydraulic Analyses An analysis of the hydraulic characteristics of flooding from the riverine source studied was carried out to provide an estimate of the elevations of floods of the selected recurrence intervals. S