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. . :. . . . . ,. . I. . . . . . . I: '. . . . ~ . . I. . . . . . . . . . . . . I. '. i. . . I. . . . . I. . . . . . . STUDY AREA DESCRIPTION Communitv Descriution The Town of Nucla is located in southwestern Montrose County. The county is bordered by Mesa and Delta County on the north, Gunnison and Ouray County on the east, San Miguel County on the south and the state of Utah on the west. Montrose is the County Seat of Dolores County. The population of Nuda was estimated at 656 in 1990 and 737 in 1999, corresponding to a growth rate of 1.3 percent (Demography Section of the Colorado Division of Local Government). The area mapped in the FHBM includes the incorporation boundaries as of 1974. Watershed DescriDtion The Town of Nucla is located in the Dolores River basin on the western slope of the Continental Divide. Calamity Draw flows from east to west along the southern edge of the Town incorporation limits. Several smaller tributary creeks flow through the Town. However, Calamity Draw is the only stream covered by the FHBM and because the smaller tributary streams all have drainage areas less than 1 square mile, it is the only stream covered by this designation. The creek is intermittent, flowing primarily during snowmelt and precipitation events. The Calamity Draw watershed extends along a small ridge immediately north of the Town through agricultural land south and east of Town, and generally includes most of First Park. Elevations of the watershed range from 6200 feet at its headwaters to about 5200 feet at its confluence with Cross Canyon, with the elevation of Nucla ranging from 5700 to 5900 feet. There are no USGS or Division of Water Resources gaging stations on Calamity Draw, With the exception of the town itself, the Calamity Draw watershed is generally agricultural lands with some and forested lands around the watershed periphery. Total land area of the watershed draining to the floodplain within the Town is 3.23 square miles. FloodiRl! Problems and Floodine Historv Floods in the subject watersheds normally occur during the late summer and early autumn 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. Flooding along Calamity Draw is not well documented. There has been some minor flooding along the draw that inundated pastures and fields but did not cause structural damage or personal injuries. 2