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4,6 ST, VRAIN CREEK Flood Historv. Early records of floods are fragmented and lacking in detail. Flooding occurred on St. Vrain Creek in 1864. 1876, 1894,1921,1938,1941,1949,1951,1957, and 1969. Flood of June 11164. A storm in June 1864 resulted in a flood, the effects of which reportedly 'were felt severely' in the 51. Vrain valley. Flood of May 18~'6. The Golden, Colorado Tribune of May 31, 1876 described a flood during that month as covering farmlands from 'bluff to bluff' at the junction of SI. Vrain and Left Hand Creeks, at Longmont. Flood of 31 May 1894, The flood of 31 May 1894 washed away 20 homes at Lyons. 'A day or two before Memorial Day in 1894, a steady rain began to fall which soon reached flood proportions, and the entire lower part of the town was washed away. No lives were lost . ..' This flood had an estimated peak discharge of 9,800 cubic feet per second (ets) at Lyons, a flood of suc:h magnitude as to have less than a 1 -in-50 chance of occurrence in any year. South St. Vrain Creek contributed the greater part of the flood. Flood 30-31 July 1919. In late July 1919, a series of severe thunderstorms caused flash flooding along SI. Vrain Creek. From the Lyons Recorder dated 2 August 1919: 'The heaviest and most destructive cloudburst. . . in the memory of the oldest inhabitant visited Lyons on W4~nesday (July 30) between 2:30 and 3:45 p.m. It took out all the bridges on the Nann SI. Vrain for about 5 miles up and 5 miles downstream. The Longmont and Lyon:! water mains up the canyon were tom out in many places. . . miles of road were tom out along the narrow canyon. The people living along the banks of the river were flooded out, and many abandoned their homes for higher ground and safety . . . homes (in the lower part of town)... were in a roaring sea of water 2 and 3 feet deep.' Another crest on the following day again flooded houses in the lower areas of town and washed out 300 yarels of railroad track east of Lyons, The peak discharge on 30 July was later computed to bll 9,400 ets. The right bank of North St. Vrain Creek was flooded to a width of 300 feet. Flood of 2-7 JunE11921. Heavy rains combined with snowmelt runoff caused flooding in the Longmont area early in June of 1921. A total of 5,87 inches of rain was recorded at Longmont from 2 to 7 June. The Boulder Camera of 7 June 1921 reported that St. Vrain Creek at Longmont was 'way out of its banks' and 'three-quarters of a mile wide. Water is up to the Fanne~s Mill and the depot. All bridges in the city are out or dangerous.' The PElak discharge at Lyons was 2,020 cfs on 7 June which was not indicative of conditions at Longmont because of heavy rains downstream of Lyons. Flood of September 1938. The flood of September 1939 was confined mostly to rural areas downstream of Longmant. Colorado Flood Hydrology Manual 4.10 [RAFT