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<br />Records show that, since the turn of the century, notable high <br />flows occurred on the Uncompahgre River in 1921, 1927, 1938, 1941, <br />1944, 1947, 1957, 1973, and 1975. The largest known flood, esti- <br />mated peak flow of 5,140 cfs as recorded at the Colona stream gage <br />(approximately 20 miles upstream of Olathe), occurred approximately <br />mid-June 1921 as a result of snowmelt. Based on the results of <br />this study, the 1921 flood is estimated to have been slightly larger <br />than the lOa-year frequency flood. The only notable cloudburst <br />flood of record occurred in July 1923. Peak flows of the larger <br />historical floods on the Uncompahgre River are shown in Table 3. <br /> <br />Historical flooding in the Uncompahgre Valley, described in avail- <br />able news articles, has damaged or destroyed railroad track and <br />embankments, road and railroad bridges, roads, diversion structures, <br />and buildings and their contents. Inundation of agricultural prop- <br />erty has eroded farmlands; damaged and destroyed crops and irriga- <br />tion systems; reduced soil productivity as the result of increased <br />salinity; and deposited sand, silt, and debris on cropland and <br />pasture. Railroad and highway traffic has been disrupted, public <br />utilities damaged and destroyed, homes evacuated for as long as <br />several days, and cattle moved to higher ground to protect them <br />from the possibility of drowning. <br /> <br />According to newspaper articles from the Montrose Daily Press cited <br />in a floodplain information and urban drainage report (Reference 4), <br />notable floods occurred in the Montrose area in 1938, 1964, and <br />1967. This area includes the Cedar Creek, Dry Cedar Creek, and <br />Montrose Arroyo basins. However, no historical records of flooding <br />are available for any separate stream. Also, no historical records <br />of flooding are available for the Hieroglyphics Canyon and Happy <br />Canyon Creek basins. Figures 2 through 10 show examples of flooding <br />problems in Montrose County. <br /> <br />2.4 Flood Protection Measures <br /> <br />As of June 1980, no flood-control projects affecting floodflows or <br />flood elevations were in existence. However, the Dallas Creek <br />project, located at Ridgeway, Colorado, creates a reservoir that <br />has 80,000 acre-feet of storage, with an additional flood-control <br />storage for spring runoff of 26,000 acre-feet. A 1973 U.s. Army <br />Corps of Engineers report states that this project will reduce the <br />standard project flood of 7,000 cfs to a flow of 3,700 cfs at the <br />dam site. Although this could provide incidental flood-control <br />benefits to downstream flood plain areas, flood control is not a <br />function of this project. Therefore, any effects of the Dallas <br />Creek project were not included in this study (Reference 5). <br /> <br />Improvements such as dikes and bank protection have been made at <br />various locations along the Uncompahgre River. Some incidental <br />flood protection is provided by several irrigation canals that <br />branch off from the river at different locations upstream of the <br /> <br />~ <br />