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<br />....................................................... <br /> <br />Table 2. Computed tOO-Year Discharges by Various Methods for Approximate Streams <br /> <br /> tOO-Year Discharee Method <br /> USACE with <br />Flooding Source Location Drainage Period Regional Frequency Ridgway Resv. <br /> Area Of R . 1 Analysis2 Analysis3 <br /> egressIOn <br /> (SQ mi) Record (cfs) (cfs) (cfs) <br />Pleasant Valley Cr. @ USGS Gage Sta. 09146600 8.17 1956-67 609 782 UIS of Resv.4 <br /> (near Noel) 12 yrs <br />Dallas Cr. @ USGS Gage Sta. 09147000 97.2 1922-99 2,547 2,150' UIS of Resv. <br /> (near conf!. with Uncompahgre River) 42 yrs <br />Cow Cr. @ USGS Gage Sta. 09147100 45.4 1956-73 1,641 1,640 UIS of Resv. <br /> (Just dls of Courthouse Creek conf!.) 18 yrs <br />Uncompahgre R. @ USGS Gage Sta. 09147500 448 1903-99 6,161 4,370 2,000 <br /> (at Colona) 82 yrs <br /> <br />Notes: <br />1. Regional regression equations presented in Guidelines For Determining lOO-Year Flood Flows For Approximate Floodplains in Colorado, Version 4.0, <br />Colorado Water Conservation Board, January 1999. <br />2. Frequency analysis based on procedures presented in Guidelines/or Determining Flood Flow Frequency, Water Resources Council, Bulletin 17B, 1981 as <br />implemented in the computer program HEC-FFA, U.S. Army Corps of Engineers, May 1992. <br />3. Discharge at Colona with Ridgway Reservoir derived from Ridgway Dam and Reservoir Uncompahgre River Water Control Manual, U.S. Army Corps of <br />Engineers, Sacramento District, November 1996. <br />4. UIS of Resv. - Indicates that location is upstream of Ridgway Reservoir and flows are therefore unaffected by storage in the reservoir. <br />5. Frequency analysis results presented for Dallas Creek are based on the inclusion of the July 3 I, 1999 discharge of 3,960 cfs. This discharge is approximately <br />3.5 times higher than any previously recorded value. Exclusion of this data point from the analysis would yield a computed lOO-year discharge of 1,750 cfs. <br /> <br />8 <br />