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Historical documentation of flood damage is meager in the area of the City of Lafayette and the Town of Superior. This is probably due to the small stream size and lack of extensive urbanization. Major flood damages in the watershed are to roads, bridges, irrigation structures, and agricultural land.' Duration of flooding is brief, due to steep slopes and small drainage area. In general, peak flows last from 1 to 4 hours during a flooding period of 6 to 24 hours. . The following floods have been reported: The floods of 1876; l89l; June 3, 1921; and May 26, 1935, were caused by rapid snowmelt in the mountains and heavy rainfall in the area of Lafayette. A flood occurred in June 1896 which was reported as the maximum of record in the part of the valley near Louisville. The flood of September 2, 1938, was caused. by cloudbursts in the mountains and foothills, resulting in a flood' slightly higher than that of 1935. Using slope-area measurements,' the USACE estimated the flood discharges on Coal Creek near Erie to be 13,200, 7,800, and 3,500 cubic feet per second (cfs) in 1876, 1921, and 1938, respectively (Reference 19). The 1876 flood is the largest recorded at the Town of Brie and approximates the 100-year recurrence interval, as determined by the SCS (Reference 19), using synthetic methods for flood routing. The most recent floods in the wa~ershed occurred on June 9, 1949; May 9, 1957; and May 1969. The following are recorded accounts of flood damage on Coal Creek and Rock Creek: September 2, 1938. "Parts of the residential area in Louisville were under several inches of water, but the business district was not ~amaged. One person was killed in an automobile accident ion the flooded highway east of Louisville. The bridge at, Bmpire Drive and State Highway 42 was on the verge of failure, but was saved." June 9, 1949. "The bridge at the junction of Coal Creek and Rock Creek, 3 miles north and l/4 mile west of Brie was threatened and closed to traffic. The bridge over Coal Creek, 3/4 mile east of Superior, went out." May 1969. "Damage to land irrigation structures and agriculture totaled approxiinately $75,000." St. Vrain Creek flows through the City of Longmont in a broad channel bed of shifting sandbars bounded by banks 10 to 15 feet high. Lefthand Creek, Dry Creek No.1, and Spring Gulch flow in relatively steep, narrow channels. The overbanks of all the streams studied are relatively flat, with the exception of the north overbanks of St. Vrain Creek and Lefthand Creek, which rise more steeply. , 20