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In the region surrounding the Town of Dolores, precipitation occurs in th <br />snow with deep snowpack developing in the higher elevations. Therefe <br />spring and early sununer, runoff from melting snow presents a mod~ <br />constant flood threat, but high peak flows are not characteristic of ~ <br />runoff. Frontal type rainstorms in October 1911 caused the largest flood <br />in the drainage areas of the Dolores and West Dolores Rivers, flooding <br />the Town of Dolores. In May 1941 and June 1949, lazge snowm <br />occurred on the Dolores River. The most recent flooding occurred in ~ <br />1970, but the magnitude of flow of that flood was not recorded. <br />records of flooding events on the Dolores River aze primarily based on n <br />accounts, with indications that high water surface elevations occurred <br />1911, 1932, 1937, 1938, 1941, 1944, 1949, 1957, and 1970. Flood li <br />West Dolores River, Dolores River, and Lost Canyon Creek is usually <br />damage of bridges and irrigation structures. <br />form of <br />;, in the <br />ate and <br />~f record <br />much of <br />;lt flows <br />in 1909, <br />ss in the <br />.mited to <br />Cloudburst storms can constitute a severe flood threat; but due to small aerial <br />extent, small volutne of runoff, and short duration of this type of storm, a <br />significant flood threat is present only in the smaller drainage areas such as Lost <br />Canyon Creek those within the City of Cortez. Heavy rain along Lost Canyon <br />Creek in October 1941 caused flooding in that area. <br />Flood events on the Mancos River and Chicken Creek are usually the result of <br />spring snowmelt coupled with thunderstorms occurring through May d June. <br />Antecedent ground moisture also contributes to flood characteristic~s. High <br />ground moisture coupled with warm days and spring showers give rise tQ the high <br />flood potential. Heavy thunderstorms through the summer and fall have caused <br />flash floods. Information on historical flooding on the Mancos River in and <br />around the Town of Mancos is available primarily from newspapers. Records <br />from an early stream-gaging station located 2 miles east of town are available <br />from the Office of the State Engineer for a limited number of years beginning in <br />1921. Gaging stations are located above the town on the Mancos, West Mancos, <br />Middle Mancos, and East Mancos Rivers. Although a continuous gage record for <br />the river at Mancos does not exist, newspaper records and area str~am gage <br />records indicate that high water and major flood events have occurred since the <br />area was first settled in 1876, and particularly in 1909, 1911, 1932, 19~37, 1938, <br />1941, 1944, 1949, 1957, 1973, and 1979. According to the Mancos Times <br />Tribune, the May 31, 1979, floodflow on the Mancos River of 1,575 ~ubic feet <br />per second (cfs) was among the largest. This flow was significantly les~s than the <br />50-year recurrence interval flood (Muller Engineering, March 198~2). The <br />Mancos Times Tribune reported that the floods of 1909 and 1911 caused damage <br />to the Post Office and various commercial and warehouse structures. In 1957, <br />flood damage was largely to irrigation structures. The floods in May 1973 and <br />May 1979 (1,110 cfs and 1,575 cfs, respectively) caused substantial bank erosion <br />in and around the Town of Mancos. <br />~ <br />