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Between Canon City and Pueblor the Arkansas River valley is gener- ally narrow and the streambed well-defined, with a gradient ranging from 10 to 23 feet per mile. The river valley widens below Pueblo, varying in width from 1 to 3 milesr with a gradient ranging from 5 to 9 feet per mile. Both Anderson and King Arroyos originate south of La Junta. King Arroyo flows almost due north along the east side of La Junta in a well-defined channel, draining 25 square miles. The channel from its confluence with Arkansas River to 3rd Street has been partially improved and riprapped. The remainder is in its natural state, with the exception of large amounts of debris that have been dumped into it near 14th Street, obstructing portions of the channel. The channel has an average slope of 24 feet per mile within the study area (Reference 1). Anderson Arroyo flows northerly along the west side of La Junta to its confluence with the Arkansas River. Although Anderson Arroyo has been partially improved in La Junta, most of the channel is in its natural state. The watershed is approximately 15.5 miles long and 3.5 miles wide, with a drainage area of approximately 54 square miles. The arroyo has an average gradient of 19.4 feet per mile (Reference 1). Timpas Creek flows northerly through a broadr flat valley, drain- ing 496 square miles before joining the Arkansas River near the Town of Swink. The climate in the Arkansas River subbasin above John Martin Reser- voir varies from subhumid in the high mountain region to semiarid in the lower plains. Precipitation averages from 10 inches annually at the lower elevations to as much as 40 inches over limited areas on the crests of the mountain ranges. A large percentage of the annual precipitation in the mountains falls as snow (Reference 1). More than one-half of the precipitation over the plains occurs from April through August. 2.3 Principal Flood Problems Historical records reference many floods in the Arkansas River Valley above John Martin Reservoir. The earliest recorded flood occurred in 1826. Other floods occurred in 1844, 1859, 1864, 1869, and 1894. These floods were generally confined between Pueblo and John Martin Reservoir. Other major floods occurred at various locations in 1921, 1935, 1942, 1955r and 1965. The 1921 flood is the largest flood of record on the Arkansas River, with a peak discharge of 200,000 cubic feet per second (cfs) at La Junta (Reference 2). Floods occurred on King and Anderson Arroyos in l886r 1965r 1969r and 1972. Data on these floods and floods on Timpas Creek are not available. 5