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Flood of Mav 1973. Rainfall generally ranging to as much as 6 inches fell on the plains east of the Rocky Mountains beginning on 5 May. The Dry Creek basin received amounts ranging from 2 to 4 inches. Runoff from this general stonn contributed to considerable flooding on the South Platte River. ~ . 4.1.11 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 1864. A storm in June 1864 resu~ed in a flood. the effects of which reportedly "were fe~ severely" in the SI. Vrain valley. Flood of Mav 1876c 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 Mav 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 c .." This flood had an estimated peak discharge of 9.800 cubic feet per second (cis) at Lyons, a flood of such magn~ude as to have less than a 1 -in-50 chance of occurrence in any year. South SI. Vrain Creek contributed the greater part of the flood. Flood 30-31 Julv 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 vis~ed Lyons on Wednesday (July 30) between 2:30 and 3:45 p.m. It took out all the bridges on the North St. Vrain for about 5 miles up and 5 miles downstream. The Longmont and Lyons water mains up the canyon were tom out in many places. . c miles of road were torn 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 yards of railroad track east of Lyons. ThB peak discharge on 30 July was later computed to be 9,400 cis. The right bank of North SI. Vrain Creek was flooded to a width of 300 feet. . Flood of 2-7 June 1921. Heavy rains combined w~h snowmeR 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 ~s banks" and '~hree-quarters of a mile wide. Water is up to the Farmer's Mill and the depol. All bridges in the city are out or . Colorado Flood Hydrology Manual 4.15 fFIJfT