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H:!DROt.O:;!C ANAL:!S!S pealts. The lel'l'lth of record of oorre of the gages predates construction of several reservoirs upstream of the study reaches. "Pre-resenl'oir" data was examined and subsequently eliminated from the statistical analysis b;cause it fell outside of the 5% confidence limit of the complete record. Listed in Table 2 are discharges for the return intervals examined in this study for Parachute Creelt and the Colorado River. No further hydrologic investigationswere[Jerfor~for l:.'lisreport. More detailed discussions of the derivation of flood discharges of the COlorado River and Parachute Creelt are contained in references 1 and 2, res[Jectively. TABLE 2 f:'!.OOO D!SCHARGSS (<::ubicfeet[Jersecondl Location lO-year SO-year lOO-vear 500-year Colorado River Parachute Creek 31,200 40,400 2,350 4,400 44,400 50,100 5,600 10,000 Source: ref.1and2 Peak discharqm; for i'arachute Creek oowloP<.>d by the Soil Conservation Service are derived partially ",ith the use of the SCS TR-20 corrp.lter program which simulates rainfall flood peaks. Output from the program for 16 different watersheds triootary to the Colorado River between DeB€que and Glenwood Springs were plotted am a regional curve of drsinage area versus pealt discharge and return frequency was developed. Regional curves were also drawn for snowmelt flood events derived from stream gage data from 8 gages in the area. The sirrulatedrainfallcurvesandthesn~ltcurveswerethenconV:>inedusinga standard probability equation into one set of curvas which ",as ap[:llied to several tributaries in the area, including Parachute Creek. Regional stream gage analyses we~e used by the Corps of Enginee.s to derive flooe discharges for the indicated ret~rn frequencies for the Colorado River as well. Data from eight gages on the.Colorado River, l:.~e Roaring Fork River and Plateau Creek were used without differentiating between rainfall and snowmelt 8 9