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of record at each station are given in table 10. Comparative records at these stations for identical periods of record (June 1939-September 1965) are given in table II. A plot of mean daily flows, annual flow volumes, and ma~imum annual peaks for Arkansas River at Las Animas for the period 1940-65 is shown on plates 3 through 9. 3-06. Major f200ds of record.- During the period of streamflow records, major floods occurred on the Arkansas River in the years 1921, 1942, 1955, and 1965. The floods of 1921, 1955, and 1965 resulted. from rainstorms; whereas, the 1942 flood was the result of snowmelt runoff augmented by rainfall runoff. Brief descriptions of these floods are given in subsequent paragraphs. 3-07. Flood of June 1921.- The flood of June 1921 was the re- sult of the storm of 2-5 June 1921, which centered near Pueblo and pro- duced the flood peaks of record in Colorado above Las Animas. Weather records show that precipitation between Canon City and Pueblo was from 3 to 5 inches for the 48-hour period ending on the .afternoon of 4 June. The streams that enter the Arkansas River between Canon City and the mouth of Chico Creek, 16 miles below Pueblo, were the principal con- tributors to the flood. The flood crest increased rapidly as it pro- gressed downstream. The flood peaks of many of the tributary streams reached Pueblo at the same time and caused the maximum peaks of record at Pueblo, Nepesta, La Junta, and Las Animas. Above La Junta the effects of valley storage were obscured by the inflow from the tribu- tary streams. Below La Junta the tributary inflow was small and the effects of valley storage were evident. The peak at Pueblo, 103,000 c.f.s., increased to 180,000 c.f.s. at Nepesta and to 200,000 c.f.s. at La Junta. The peak reduced to 187,000 c.f.s. at Las Animas as a result of valley storage. 3-08. Flood of April 1942.- The month of April 1942 was one of the wettest months in the history of Colorado. The average precipita- tion of 4.35 inches was the second largest for the state at that time. This amount was exceeded only by the 5.96 inches of precipitation that occurred during April 1900. Heavy precipitation over the entire Purga- toire River watershed occurred 16-20 April; much of it in the form of snow. Rainfall during the 22-25 April period hastened the melting of the heavy snow deposits and resulted in a peak flow of 60,000 c.f.s. on the Purgatoire River near Las Animas. Precipitation over the Arkansas River drainage area above Las Animas produced a peak of 12,000 c.f.s. at Nepesta, 34,800 c.f.s. at La Junta, and 23,600 c.f.s. at Las Animas. Although there was major flooding at Trinidad, where the peak flow on the Purgatoire River reached 27,000 c.f.s., the princi- pal damage was to transportation and irrigation systems in the Arkansas River valley. 3-09. Flood of May 1955.- During the period 17-20 May heavy precipitation occurred over th~ lower mountains and plains of eastern Colorado and northeastern New Mexico and the plains of western Kansas. The precipitation over the mountainous area was principally in the 12