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<br />filled with sediment that nearly all of the present flows <br />are discharging through the new channels. Generally, <br />however, the new channels are old watercourses abandoned <br />by the river in previous years. The littered condition <br />of the channels, and the increased danger of bank erosion, <br />inundation, and resultant channel changes constitute the <br />present flood problem. <br /> <br />No urban areas are affected by floods. The principal <br />items damaged by the 1957 flood were the agricultural <br />lands and roads and bridges adjacent to, or over the <br />river. A few farm buildings were flooded. The total <br />known damages in all categories in this reach amounted <br />to slightly more than $45,000. <br /> <br />A common type of damage from the 1957 flood was bank <br />erosion. The slope of the stream ranges from 65 feet <br />per mile above Basalt to 40 feet per mile below Basalt. <br />Velocities probably in excess of 10 feet per second oc- <br />curred during the 1957 flood. The banks are composed <br />largely of sand, gravel, and cobbles overlain by a com- <br />paratively thin mantle of soil, and are quite erosible. <br />Spoil-type dikes, constructed by local interests with <br />material bulldozed in the process of channel clearing, <br />proved to be very erosible. <br /> <br />A substantial percentage of the total damages were due <br />to overtopping of the low banks and the inundation of <br />pasture and croplands. The banks in most instances range <br />from only 2 to 5 feet in height. In 2 locations, where <br />old channel areas have been reclaimed, considerable volumes <br />of overflow and widespread flooding resulted from bank <br />overtopping at the upper ends of the areas. <br /> <br />More than one-half of the known damages in the 1957 flood <br />were caused to roads and bridges in the area, with nearly <br />$24,000 of damages being caused to 3 bridges and their <br />abutments. Two of these were public bridges and have <br />since been restored. A third bridge, which was private, <br />was completely destroyed and has not been replaced. <br /> <br />Aspen is known to have a long history of flooding, the earliest <br />occurring in 1880 (Reference 6). The flood of June-July 1917 is <br />considered the most severe in the Aspen area, with a peak discharge <br />of 3,170 cfs on the Roaring Fork River. The largest recorded flood <br />on Castle Creek near Aspen occurred in 1918, with a peak flow of <br />1,090 cfs; on Hunter Creek, the largest flood occurred in 1953 <br />with a peak flow of 1,010 cfs. The highest peak flow on the Crystal <br />River above its confluence with Avalanche Creek was 3,980 cfs, <br />recorded in 1957. A peak of 836 cfs for Maroon Creek was recorded <br />in 1980 (Reference 7). In 1983 and 1984, large snow depths in the <br /> <br />7 <br />