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<br />I <br />I <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />I <br />I <br />I <br />I <br /> <br />I <br />. <br />I <br />I <br />I <br />I <br /> <br />The peak discharge of the St. Vrain at Lyons was 1650 cfs at 1:00 <br />AM on September 3, while the peak discharge at the mouth of the <br />St. Vrain was estimated as 8,360 cfs at 6:00 PM the same day. <br />Newspaper reports indicated that "scores" of families along the <br />St. Vrain in the Longmont area were forced from their homes along <br />the Creek by the high water. Two bridges on State Highway 52 <br />were also washed out and the bridge approaches damaged (Reference <br />4) . <br /> <br />Railroad and highway bridges near Longmont were also damaged. <br />Farmers in the valley between Lyons and the mouth of the St. <br />Vrain suffered crop losses as well (References 1, 2, 3, 5, 6). <br /> <br />1951 FLOOD <br /> <br />Three to five inches of rain fell on the entire St. Vrain basin <br />during the night of May 8-9, 1957. The St. Vrain at Lyons peaked <br />at 3,060 cfs about 1 pm on May 9, while the St. Vrain at the <br />mouth peaked at 9,450 cfs at 12:15 am on May 10. Two bridges <br />were destroyed. approaches to several bridges were washed out, <br />and several irrigation diversion structures were damaged or <br />destroyed (References 1, 2, 3, 4, 6). <br /> <br />1941 FLOOD <br /> <br />Cloudbursts occurred over both North and Sou th St. Vrain Creeks <br />on June 22, 1941. Peak discharge at Lyons was estimated as <br />10,500 cfs. A resident of Longmont was killed at his cabin in <br />South St. Vrain Canyon by the flood. Three homes in the canyon <br />were destroyed, and several homes in Lyons were flooded. Damage <br />was reported to the roads in both North and South St. Vrain <br />Canyons. The road damage, in conjunction with a bridge washout, <br />caused the road in the South St. Vrain Canyon to be closed for <br />several days. The "swinging bridge" in Lyons was also destroyed <br />by the floodwaters (References 1. 2, 3, 4, 5, 6). <br /> <br />1969 FLOOD <br /> <br />Heavy rainfall combined with snowmelt to cause prolonged high <br />flows On the St. Vrain. The worst flooding occurred on May 7-8, <br />and June 15-21, 1969. Roads and bridges along the stream were <br />extensively damaged, streambanks eroded, and farmlands flooded. <br />The peak discharge at Lyons was 2,900 cfs on May 7. Peak <br />discharge at the mouth was 10,300 cfs on May 8 (References 1, 2, <br />3, 4, 6). <br /> <br />1949 FLOOD <br /> <br />Nearly 3 inches of rain which fell in the St. ,Vrain valley on <br />June 4, 1949 caused the St. Vrain to peak at 2,970 cfs at Lyons. <br />Peak discharge reached approximately 6,700 cfs at Longmont. All <br />bridges between Longmont and Lyons were either impassable or <br />under close watch by State Highway Department crews, while two <br />bridges were destroyed entirely. Thirty-five people were <br />evacuated from the St. Vrain floodplain. The road in the South <br />St. Vrain canyon was closed as a precautionary measure. The <br />Burlington Northern Railroad track to Lyons was also rendered <br />useless as floodwaters had destroyed the roadbed east of Lyons <br />(References 1, 2, 3, 5, 6). <br /> <br />Following are selected newspaper headlines and articles dealing <br />with several of the major floods along the St. Vrain. These <br />newspaper accounts were taken from the Camp. Dresser, McKee, Inc. <br />report (Reference 5) and from the Water Resources Consultants, <br />Inc. report (Reference 4). The Colorado Water Conservation Board <br />and Boulder County supplied the historical photographs. <br /> <br />1951 FLOOD <br /> <br />Heavy rains occurred in the St. Vrain basin during the afternoon <br />and night of August 3, 1951. Lyons received 6.3 inches from a <br />cloudburst which began about 6 p.m. Flooding resulted along the <br />South St. Vrain, and along the reach from Lyons to the mouth of <br />the St. Vrain. Floodwaters destroyed several sections of road in <br />the South St. Vrain Canyon and inundated businesses in Lyons. <br /> <br />-7- <br />