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residents should continuously monitor the lateral for spilling, leakage and embankment failure. Locations for emergency breaching should be designated along the lateral at points where resultant damages would be nil. Procaution to the possiblity of flooding ~long the Brush Lateral, rather than assurances that the lateral cannot flood,is advisable. Flood plain roughness factors (Hanning's "n") used in these corr.putations were selected based on field inspection of the actual flood plain conditions. The roughness factors used in this study arc listed below: Hydrologic Analysis The hydrologic analysis was completed to estimate the peak discharge-frequency relationships for floods of 10-, 50-, 100- and SOO-year recurrence intervals for Beaver Creek. The flood peak estimates were based on a statistical analysis of recorded stream flow records for comparable drainage areas in the high plains area of eastern Colorado, western Kansas and southwostern Nebraska. The estimates prepared for this report were made utili- zing the statistically analyzed data of the U. S. Geological Survey (Reference 4). A detailed description and summary of the hydrologic analyses and computations arc provided in Technical Addendum NO. l, on file with the Colorado Water Conservation Board. Channel area 0 , 0.035 Overbank area {fields) 0 . 0.030 Developed overbank areas (within city) : 0 . 0.050 A detailed doscription of the hydraulic analyses completed as a part of this study is included in the Technical Addendum NO.2, on file with the Colorado Water Conservation BOard. FLOOD PLAIN DELINEATION The flood profile elevations and flood plain limits shown in this report can be easily transferred to field locations by simple survey methods using the established monumentation or by scaling from physical features shown on the map. To determine the depth of flooding or the flood plain limits at any location in the field, the following procedure should be used: Hydraulic An"ly>>i" Locate the ground point at which the depth of flooding cr the flood plai"- lil".it is to b" ",gtablish<"d on th(> 1" Andly~e8 oi t.l,,,, hy<h""ulic characteristics of Deaver Creek ....ere completed to provide estimates of the water surface elevations for the selected recurrence intervals. The water surface elevations were computed using the Corps of Engineers' HEC-2, Water Surface Profiles step-buckwutcr computer program (Reference 3). Cross ~ectiong for the backwater analysis of Beaver Creek were taken from the topographic maps prepared for the study. Digitized cross sections were secured in the area south of County Road DLD at the time the topographic maps were compiled. The locations of the cross sections utilized in the study are shown by a reference point on the Flooded Area Hap, Plate 3, and the Flood Profiles, Plates 4-10. The reference points, flood elevations i:lnd discharqes are tabulated in Table 2, Flood Frequency, Elevation and Discharge Data. ~ 400' flooded area map. Determine the elevation of the water surface at thc se- lected qrounu point from Table 2 by interpolating between the water surface elevations given for two adjacent cross- section reference points. Using the closest monument for elevation control, determine the water surface elevation at the ground poLnt by stan- ddrd labeling technique. The flood plain limit is estab- liShed where the water surface elevation intercepts the ground surface. -13_ -14-