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For North Turkey Creek, the equations presented in the Miller and Thomas report were used to develop revised discharges for the 10-, 50-, 100- and 500-year floods (Reference 48). For Bear Creek, revised peak flows were developed from a flood frequency analysis at the stream gage in Morrison as presented in a report, entitled "Flood Hydrology of Foothill and Mountain Streams in Colorado" by R. D. Jarrett. Revised peak flows for the ungaged portions of Bear Creek were determined by utilizing the following equation with peak flows at the Morrison gage: Qs = QG (As/AG)ll = Peak flow in cfs at the ungaged site Peak flow in cfs at the Morrison gage Total drainage area at the ungaged site Total drainage area at the Morrison gage exponent where Qs QG As AG n = = = = The exponent n was derived from the discharge-drainage relationship obtained by utilizing the Thomas and Miller regression equations and specific basin information at the sites on Bear Creek from Morrison to the Jefferson county line. The detailed study reach at Morrison was not revised because changes in peak flow values between those originally completed for the FIS and changes computed by Jarrett would not produce significant changes in elevations. The peak discharge-frequency relationships utilized within this study for Ralston, VanBibber, and Leyden Creeks within the City of Arvada, were obtained from the previously mentioned Major Drainageway Planning Report (Reference 37). The peak flows associated with Little Dry Creek and its tributaries can be obtained from the report entitled "Flood Hazard Area Delineation, Little Dry Creek," (Reference 49). The flows presented in the Major Drainageway Planning Report (Reference 37) were generated using the Massachusetts Institute of Technology Catchment Program (Reference 44). The flows reported within the study represented 2-, 5-, 10-, and 100-year return frequencies. Assurances could not be made by the City of Arvada that Leyden Lake would continue to be maintained and operated. Arvada Reservoir is a drinking water storage facility with its water level maintained at maximum elevation, thereby negating any flood routing ability. The peak flows used in the floodplain analysis do not represent any routing and resultant flood attenuation through these two reservoirs. However, assurances were made for the other previously mentioned reservoirs, and therefore, the floodflows were routed through those reservoirs. Since Ralston, Van Bibber, and Leyden Creeks were partial detailed studies based upon the Major Drainageway Planning Report, the flows used in the hydraulic analysis were in accordance with the flows used in that report. Furthermore, many of these flows are based upon ultimate basin conditions in accordance with reasonable projections of land use by Jefferson County and the City of Arvada. The use of future floodflows is standard procedure for the UDFCD. 27