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Gaqe Locatiorl DralrlaqeArea (squaremiies) Period of Record Info~tlon from these 9ages ~as used Irl the hydrologic analysIs conducted during this study. Informatlon on past floods was obtaIned from Corps of Engineers flood records. The. photograph base for the flooded areas are <lerl<ll photographs taken during the flood period in May 1973 by the Colorado Water Conservation Board and the Corps of Engineers. Cross section data utilized In this study was supplied by the Corps of Engineers. High wator mark data from the flood of ~y 1973 ~as coordinated and obtained In part by the Colorado Water Conservation Board ~Ith sup- plemantallnfo....aTlonbytheCorpsofEnglrleers,theU.S.Gaofog1cal Survey, and the Bureau of Reclamation. U. S. GeologIcal Survey 7.5 mInUTe quadrangle maps ~Ith 10 foot contour Intervals were also used !nthesTudy. South Morgan Tablet Platte River Stream GlIge and WashingTon Counties, ~ta In Colorado Weldona ForT Morgan &Izac 13,245 14,810 16,852 October 1952 to present 1944 Through 1958 October 1916 1'0 present The weSTern boundary of the South PlaTte River basIn Is formGd by The ConTInenTal Divide with elevations up to about 14,200 feet and the Laramie Range ~lth elevatIons up to aboUT 10,000 feet. At the southwestern corner of the basIn, the mountain area knowrl as South Park Is located. This area Is nearly flat and has an elevation of about 10,000 feet. It Is surrounded by mountain ranges varying In alevation froM 12,000 to 14,000 feet, The Tarryall Mountains fo.... the northeast boundary of the South Park area, ElevatIons In the plains regIon vary from approxImately 7,000 feet along The foothills to approxImately 4,070 feet at the Washington-Logan County line. Flood Season and FlOOd Characteristics Flooding along the South Platte River In Morgen and Washington Count!es no~lly occurs from May through September with the most frequent flooding occurring during June. Annual peak discharges, however, have been recorded from February through Oetober. Floods In Morgan and WashIngTon Counties normally occur under non-Ice <lffoctedoondltions, Icej"ms, r.owever, are possible even tr.ough thair historical frequency of occurrence Is rare. Flood~eters on the South Platte River in Morgan and WashIngton Counties can result from Intense locallzodralnfall or general raIns, elth~r of ~hlch ~ay be au~"ted by sno~lt. The Intense raInstorM floods resulT from Intense rainfall over areas of relatIvely small are"1 extent. These storms can produce extremely rapid concentra- tlonsof floodwaters and ensuant rapid rIses Instreamtevels. Because of little warning tIme prIor to streams attaining flood stages, thIs type of storM can produce floods whiCh are e~tr~mely hazardous, This type of flood produces high peek dIscharge on tribu~ taries In the gener<ll vicInIty of the raInstorm. The discharge, DevelopmenT on the Flood Pf~ln The South Pfatte River flood plain In Mor~an and Washington Counties Is uti I Ized primarily for agricultural purposes. Except for the areas adJaCBrlt to Incorporated communities such as Fort Morgan, existing flood plaIn development 15 moSTly farmsteads and ranch buildings, Source of Data and Records A conSiderable amount of hIstoric stream gage data does ewlst for the South Platte River which Is pertlnerlt to Morgan and WashIng- ton Counties, The U. S. Geological Survey has published Information col Ie<:ted et the South i"1<lttc River STre<lm gages In Morg<ln County. , ,