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<br />on the Big Thompson River caused damage in 1864 and 1894, but no discharge or damage <br />estimates were recorded. Floods also occurred on the Big Thompson River in 1919, 1923, <br />1945, and 1949 with discharges of 8,000,7,000,7,600, and 7,750 cfs, respectively. <br /> <br />Approximately 13 floods have occurred in Loveland on the Big Thompson River since <br />1864. These floods occurred in 1864, 1894, 1906, 1919, 1921, 1923, 1938, 1941, 1942, <br />1945, 1949, 1951, and 1976. All but the 1919 flood did damage to crops, homes, and <br />businesses in the Loveland area. On June 9, 1921, the Colorado and Southern Railroad <br />bridge was destroyed due to heavy rains on June 2 through 7, 1921. On June 4 through 7, <br />1949, heavy rains in the headwaters area of the Big Thompson River basin caused a flood <br />with a magnitude of 7750 cubic feet per second (cfs), as estimated at the Loveland station. <br />Although considerably less than the 100-year flood discharge of 19,000 cfs, lowland areas <br />just west of Loveland were damaged (Reference 13). <br /> <br />The largest floods recorded at Loveland have also been the most recent ones. On August 2 <br />and 3, 1951, intense rains over much of the Big Thompson River basin caused a dam to <br />break on the Buckhorn Creek on August 3. This caused severe flooding from the mouth of <br />Buckhorn Creek to the mouth of the Big Thompson River, especially through the Loveland <br />area. Approximately 1 mile of U.S. Highway 34 was destroyed just west of Loveland. <br />Irrigation works were destroyed, crop loss was heavy, and much sediment and erosion <br />damage occurred. The lives of four people were lost and many were left homeless. Total <br />damages from the flood were estimated at $602.000. The estimated discharge from this <br />flood was 22,000 cfs at Loveland, larger than the I-percent annual chance flood discharge <br />of 19,000 cfs (Reference 13). <br /> <br />Floods have been recorded in the Boxelder Creek watershed on 13 occasions since 1900. <br />On August 1, 1961, a storm with a frequency of 2- to I-percent annual chance caused an <br />estimated $76,150 in damage in the Wellington vicinity. In May and June 1967, two <br />overlapping 4-percent annual chance storms caused an estimated $46,100 in damage and <br />took four lives in the Wellington vicinity (Reference 8). <br /> <br />Buckhorn Creek has flooded on several occasions. The largest floods were in 1923, 1938, <br />1948, and 1951 with discharges of 10,500, 10,200, 5,750 and 14,000 cfs, respectively <br />(Reference 7). <br /> <br />Notable floods on the Cache La Poudre River in the study area occurred in 1844, 1864, <br />1884, 1891, 1904, 1923, and 1930. There were apparently three large floods of <br />comparable size in 1864, 1891, and 1904. All of these floods peaked near 21,000 cfs. The <br />1904 flood was probably the worst flood in terms of dollar damage (Reference 6). The <br />snowmelt runoff from 1983 produced a peak near 7,000 cfs. This was the highest peak in <br />53 years. Extensive channel damage occurred because of the prolonged duration of the <br />runoff. A rain-on-snow event in April 1999 resulted in a peak flow of 6,270 cfs. <br /> <br />The Cooper Slough floodplain is predominantly flat. Channel capacity is limited in places, <br />promoting overbank flows and divided-flow conditions. Channel flow is restricted by <br />relatively small culverts at Vine Drive, the Colorado and Southern Railroad (C&SRR), and <br />State Highway 14. Due to an undersized culvert at State Highway 14, a ponded area will <br />form north of the highway, and eventually overtop the highway during storm events. In <br /> <br />15 <br />