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The hydrologic analysis adopted for use in this study for Sand Creek were obtained from a U.S. Soil Conservation Service (SCS) Flood Hazard Analysis report (Reference 9). The SCS report used SCS hydrologic methods to develop peak discharges for the lO-, 50-, and 100-year recurrence intervals. Field reconnaissance and the analysis of current land use maps of Colorado Springs were reviewed by the study contractor to ensure that the SCS curve num- bers (CN values) were applicable to development in the city. These checks showed no significant changes in land use compared to those used in the SCS report. The 500-year peak discharge was obtained by extrapolating the 10-, 50-, and 100-year peak discharges on log-probability paper. ........ - Peak discharges for Bear, Camp, Cheyenne, and Cottonwood Creeks, and South Shooks Run were obtained from hydrologic information compiled in a COE report cited earlier (Reference 6). The hydrologic analyses contained therein utilized a synthetic unit hydrograph method to obtain flow rates for the 10-, 50-, and 100-year flood- flow rates. Basin data (such as slope, area, soils, channel lengths, and land uses) were reviewed and found to be accurately estimated for each basin associated with the above streams. The SOO-year peak discharge was obtained through extrapolation of the 10-, 50- and 100-year flood results on log-probability paper. Rainfall patterns and amounts were obtained for each of the above basins using the National Oceanic and Atomspheric Administration (NOAA) data (Reference 10). Flows resulting from this analysis were also checked with those obtained using hydrologic methods outlined in Manual for Estimating Flood Characteristics of Natural Flow Streams '(Reference 11) and showed good correlation. For Kettle and Pine Creeks, and tributaries of pine Creek, peak flow rates were obtained using the same document (Reference 11). The hydrologic results for Douglas Creek (North and South), Mesa Basin and BDckrimmon Basin drainages, Spring Creek, and for Templeton Gap Floodway and its tributaries were developed using an SCS report entitled Procedures for Determining Peak Floods in Colorado (Refer- ence 12). This methodology is consistent with those outlined in the City of Colorado Springs storm runoff criteria manual (Reference 13), and has been used widely to determine design capacities for flood- control projects throughout the city. Drainage basin studies for all basins except Spring Creek were reviewed to check'their adequacy for use in this study. In all the studies reviewed, future develop- ment conditions were assumed to obtain the 100-year frequency flow ~ rate. Field checks wete carried out to check changes in land use since completion of each drainage study, channel alignments and major hydraulic structures which could affect each basin's hydrology. The hydrologic analyses contained in the drainage basin studies accurately estimated the ~pO-year peak discharges. I The assumption of fully developed conditiops in each basin was acceptable for use I 14