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Garfield County is known to have a long history of snowmelt and summer cloudburst floods, but limited definitive data on specific floods are available because flooding largely occurred on farmland and was seldom reported. Records indicate that 12 snowmelt floods and 15 cloudburst floods occurred in Garfield County since the turn of the century. Two snowmelt floods were recorded during the last two decades of the 19th century. A snowmelt flood that occurred on the Colorado River in 1884 is generally considered the most severe known, with a 300-year recurrence interval, and a flood that occurred in 1917 is judged the most severe of record on the Roaring Fork River, with a 80- to 90-year recurrence interval. On both streams, runoff was au~ented by general rain during the flood period. The most severe cloudburst flood in Garfield County occurred in the Rifle area in August 1930. Convective type cloudburst storms that result in damaging flood runoff can frequently be expected in Garfield County, but little information on contributing precipi- tation or peak flow is available. Cloudburst runoff from tributary washes may generate mudslides. Some areas in Garfield County are subject to sheetflow; that is, broad, shallow overland flooding generally less than 2 feet deep. Water-surface elevations of flooding in these areas are essentially independent of those along adjacent stre~nways and are affected principally by barriers to flow in the flooded areas. 2.4 Flood Protection Measures There are no flood control projects that afford protection to the study area. There is a small amount of upstream storage, but it is operated for water conservation and thus provides only incidental flood protection downstream. The Bureau oOf Reclamation diverts water from the Roaring Fork River Basin toO the Arkansas River Basin upstream from Garfield County, but diversions are usually curtailed during periods of high runoff. Irrigation use also serves to reduce main stem flows, but not in significant amounts. Thus, reduction of peak flow along the Colorado and Roaring Fork Riv.ers in Garfield County is uncertain and unlikely under existing conditions. The flood control and related water resources development problems of the Upper Colorado River Basin have been under study by the U.S. Army Corps of Engineers for a number of years. No projects, how- ever, are presently proposed to protect areas of Garfield County. A study published in 1971 (Reference 1) contains a reconnaissance type plan that identifies for future detailed study two potential storage projects that would provide flood control benefits in Garfield County as well as an area for possible future watershed treatment measures. 7 ? ( ~ ~ r ,'"