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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Land uses are primarily urban development in the western portion of the county and rural development and agricultural uses in the eastern portion of the county, The South Platte and Clear Creek watersheds extend to the continental divide and include both mountainous topology and urban development. Perennial streamflow and flood discharges are influenced by numerous storage facilities and reservoirs, The Big Dry Creek watershed is located at the far northwestern corner of the county, and includes a portion of Jefferson County, The watershed is comprised primarily of urban and semi-urban development, and includes several smaller tributary streams, The eastern portion of the basin is characterized by streams that originate in Elbert and El Paso Counties along the Monument Divide and flow north across the county, The upper portion of the basins are characterized by rolling foothills vegetated with grasses and stands of Ponderosa Pine, The lower portions of these basins are generally irrigated and non-irrigated farm lands and semi- arid prairies with a gently rolling topography, Flooding Problems and Flooding Historv Floods in the subject watersheds normally occur during the months of May through August and are caused primarily by intense localized cloudbursts or thunderstorms. Typically, these floods have high peak discharges with low volumes over short durations and there is usually a very short window of opportunity for flood warning and evacuation once a major storms hits the area, Less damaging floods can also result from rapid melting of mountain snowpack in the spring and early summer months, especially on the larger drainageways, A combination of rainfall and snowmelt can sometimes prove to be the worst flooding scenario for Colorado's mountain streams. There is a well documented history of flooding within the county. Since 1844, when the first records were kept, there have been eleven devastating floods on the South Platte River, three on Clear Creek and three each on Box Elder Creek, Comanche Creek and Bijou Creek, The most recent floods on the South Platte River occurred in 1912, 1921, 1933, 1935, 1942, 1965 and 1973, with a maximum discharge of 40,300 cfs at the Denver gage during the June 16/17, 1965 storm event. Flooding events early in the century prompted the design and construction of several flood control reservoirs, Cherry Creek Dam, located in the southern metropolitan area on Cherry Creek, was completed in 1950, The 1965 flood prompted the construction of Chatfield Dam, located in the southwestern metropolitan area, in 1973, Bear Creek Dam, located in the western metropolitan area, was completed in 1979, Clear Creek experienced floods in 1888, 1933 and 1956, with a peak discharge of 8,700 cfs at the Golden gage during the 1888 flood. No significant flood control dams are located within this basin, Stanley Lake, located in the northern metropolitan area, serves as a flood control reservoir for Big Dry Creek, Several levees have been constructed, primarily along the South Platte River and Clear Creek, In addition, under the auspices of the Urban Drainage and Flood Control District, most municipalities have been proactive in construction of detention and conveyance facilities for urban development. The municipalities have also adopted ordinances to govern development within floodplains, 3