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<br />Examples of snowmelt flooding occurred at Redstone on the Crystal River, at Delta on the <br />Gunnison River and at Dolores on the Dolores River. In Redstone, the levees that were constructed <br />following the 1984 flood season prevented floodwaters from entering the community. However, lower <br />portions of the system were threatened significantly. At Dolores, the non-engineered levee system was a <br />major concern. As water approached the top one foot of the levee system, infiltration could have begun <br />and structural failure would have soon followed. Just upstream of the levee system in unincorporated <br />Montezuma County, residents sandbagged the streambanks so that floodwaters would be repelled. <br /> <br />Rain on Snowmelt Floodinl: <br /> <br />Rain on snowmelt flooding occurs most often in Colorado during the month of May. It is at this <br />time of year that large general rainstorms occur over western Colorado. These rainstorms are most often <br />caused when warm moist air from the Gulf of Mexico begins pushing far enough north that it begins to <br />affect western weather. In combination with this movement of air mass is the continued possibility of cold <br />fronts moving into Colorado from the Pacific Northwest. When these weather phenomena collide, long <br />lasting general rainstorms can often occur. Rain on snowmelt exacerbates an already tenuous situation as <br />snowmelt waters rush down heavily incised stream channels. Any abnormal increase in flow from other <br />sources usually causes streams to leave their banks. <br /> <br />Rain on snowmelt flooding occurred at Paonia on the North Fork of the Gunnison River. The <br />rainfall which occurred over a 5-hour evening period on May 28, 1993 caused the North Fork of the <br />Gunnison River to reach its highest level since the 1984 flood season. Many miles of agricultural land <br />experienced severe bank erosion in unincorporated Delta County. The stone riprap at Paonia's wastewater <br />treatment plant experienced severe damage as did the bank armoring at Huff Addition #1 (a subdivision). <br /> <br />'0 <br />, <br /> <br />I <br />~ .. <br /> <br />North Fork of the Gunnison River near Somerset <br />May-June 1993 <br /> <br />CFS in Thousands -channel capacity est. at 7000 <br /> <br />Il,OOIIer. <br />.,~ <br />, <br />g, <br />, <br /> <br /> <br />7 . ...... ....... - ....... .. ... .... ....... ..... ....... <br /> <br />3 <br /> <br />~~~V~N~~~~OO~~~~~~101112131.'51117'll'~~U <br /> <br />Prepare<1on Jun. 23rd bV <br />Division 01 Waler Resources <br /> <br />Days <br /> <br />6 <br /> <br />j <br />