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DE~CRIPTION OF THE STUDY ARE~ the T~sk Force on feder~l Flood Control Pol icy, House Document No, 465 {89th Congress, August 10. 1966), especi~l1y Recommendat ion 9(c), Regulation of Land Use, which reco~nded the prepar~tion of preliminary reports for guid~nce in those areaS where assistance is needed before a fu 11 floOd pi a i n i nformat i on report can he prepared or were a f~ 11 report is not scheduled. A~thority for funding flood plain management stUdies is pro~ided by Sect10n 6 of Public Law 83-566, which authorizes the U.S. Department of Agriculture to cooperate with other feder~l, state and loc~l agencies to make investig~tions and surveys of the watershedS ~nd rivers ~nd other w~terways as a basis for the development of coordi nated programs. In carrying out flood plain management studies, the Soil Conservation Service is being responsive to Exec~t ive Order 11988, entH led "flood Plain Management", and Exec~t i ve Order 119'10, ent i tied "Protect i on of Wet landS" {both effective M~y 24, 1977). 6~sin Characteristics This study invol ves five tributaries to the Color~do River total ing about 17.6 miles of stream, The tributaries Me located north of t~e ColoradO River. Their norther~ bo~ndaries re~ch an ele~ation of abo~t 7,800 feet along the Grand liogback north of Silt. Thesetrioutariesflow in a ~otltherly di rect i on through the town of Si 1t then on to the Co 1 orado River at an elevation of about 5.400 feet. The topography is prim~rily a hogback cut by watercourses whiCh form steep c~nyons. They open on to alluvi al fans which provide the sett i ng for the town of Silt. The climate of the area is influenced by Pacific storm systems th~t move from west to east. The ne~rest national weather station, representative of the study area, is at Rifle, The mean annu~l temperature is 470f witn about 10~ days 01' grow; ng season between the spring and fall 320F frost occurrences. The ITJI.'dn annual precipitation is just over 11 inches. This increases to about 12 inChes at the higner elev~tions of the northern boundaries. Wintertime precipitation is usually in the form of snow during OctOber to early April. The soils include Torriorthents-Rock Outcrop at the higher elevations and Potts, lldefonso, and Olney in the lower part of the basins. The ~eologic formations include s~ndstones of the Mesaverde along the hogback and WasatCh South of the hogbac~. The nigher ridges have pi nyon ~nd juniper interspersed with sagebruSh. WillowS and cottonwoods grow along the streams, There is a conSiderable amount of irrigated pasture anrl cropland along the middle and lower reaChes of the basins. -3- -,-