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III distribut~on. At each of 15 USGS gag~ng stations with at least 15 years of record, two annual peak flood series were determined, respectively, for the rain events and snowmelt events from streamflow charts. Three statistical parameters, the m~an, standard dev~ation, and skew, which dehne che log-Pearson Type III distribution, were then computed for each type of flood event. The statistical parameters are intuitively dependent on watershed character~stics and hydrometeorologic cond~c~ons ~n che reg~on. Two bas1.n parameters, drainage area and mean watershed elevat~on, which most significantly affect the magnitudes of floods, are regarded as independent variables in the discharge prediccive regression analyses. The regression equations, including only che significant independent variables for each type of event, were used co compute the flood-frequency curve aC any ungaged site, given the drainage area and mean watershed elevation. These two frequency curves, one for rain events and the other for snowmelt events, were then statistically combined to give a composite flood-frequency curve that defines the flood-frequency curve for the ungaged site in question. Discharges for streams with less than 15 square miles of drainage area were calculated using the Colorado Urban Hydrograph Procedure (CURP) (Reference 14). The 10-, 50-, and 100-year discharges were calculated directly, whereas the 500-year was estimated by extrap- olation. Peak discharges at selected locations in the study area were obtained by rout~ng CURP flood hydrographs for each subbas~n. Peak discharges for the South Platte River were developed as part of the Flood Insurance Study for Douglas County (Reference 2). In that study, a log-Pearson Type III analysis (Reference 13) was used to calculate the discharges. Streamflow data from USGS stream-gaging stations located at South Platte (gage No. 06707500) and below Cheesman Lake (gage No. 06701500) were used in the frequency analysis. The hydrologic analyses for Lena Gulch upstream of West 6th Avenue, Jackson Gulch, Kenneys Run, and Clear Creek upstream of the Burlington Northern Railroad were developed as part of the Flood Insurance Study for the City of Golden (Reference 1). In that study, the peak discharges for Clear Creek above the Burlington Northern Railroad were obtained from the COE, Omaha D~strict (Reference 15). The COE established peak discharge- frequency relationsh~ps for floods of 10-, 50-, 100-, and 500-year recurrence intervals. A log-Pearson Type III analysis (Reference 13) was conducted on the discharge records for che Clear Creek USGS stream gages at Golden (1911-1976) and Derby (1934-1976); however, the statistical parameters compuced by these methods were not suffic~ently reliable to pred~ct che frequency of extreme events. In lieu of a discharge-frequency analysis, a rainfall-runoff approach was used. The Massachusetts Institute of Technology Catchment Model (Reference 16) 10