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. 0659 . .. . .f occurred on September 30, 1904. Recorded data for moderate as well as major floods are available for the period 1921 to date. All floods which have exceeded the existing channel capacity of 15,000 cubic feet per second at Trinidad since 1921 are liste\'l in the following tllble.. Major floods are discussed in detail in appendix B. TABLE 3 PURGATOIRE RIVER FLOODS TRINIDAD, COLORADO 1921-1950 Flood Year . . Date of Peak Peak Discharge 1921 1923 1925 1927 1927 1928 1942 1950 June 4 , October 1 July 22 July 29 August 23 August 17 Aprii ~3 AuguSt 2 (1)18,000 19,800. 33;000 20;000 19;600 15.300 35 ,OOO~ 23,900 (1) Estiinat~d. 38. Flood frequency. - For the purpose of economic evaluation of flood damages under existing conditions and with proposed improvements in operation, curves of probable flood occurrences were constructed by the procedures outlined in a paper entitled "Statistical Methods in Hydrology," by Leo R. Baird, Office, Chief of Engineers, dated July 1952. During.the period of record, 1921 through 1950, eight floods have ex- ceeded the channel capacity of 15,000 cubic feet per second at Trinidad. In addition to these flood peaks, 13 peak. discharges occurred in the categor,y 10,000 to 15,000; and 30 in the categor,y 5,000 to 10,000 cubic feet per second. 39. This analysis indicates that under existing conditions, the channel capacity of 15,000 cubic feet per second at Trinidad would be equaled or exceeded once in 4 years, and the peak discharge of the maxi- mum flood of record, 45,400 cubic feet per second, would be equaled or exceeded once in about 37 years. 14' ;:;;,.