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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />I. INTRODUCTION <br /> <br />Purpose and Scope <br /> <br />This report has been prepared for the Urban Drainage and Flood Control District <br /> <br />(UDFCD) and the City of Arvada (City). It delineates the potential hazard associated with <br /> <br />a 100-year flood on the channel of Moon Gulch. The flood plains are deemed accurate <br /> <br />within the limitations of hydrologic methodology, water surface profile computations, and <br /> <br />the scales of the mapping utilized. The report assumes that the drainage basin is fully <br /> <br />developed and that the channel configuration is that which is in existence in 1990. The <br /> <br /> <br />capacities of all culverts, storm sewers, and bridges have been evaluated, and it has been <br /> <br />assumed that all facilities would remain free of debris during flooding. <br /> <br />This report was prepared for the guidance of local officials in planning the use and <br /> <br />regulation of the flood plain. The report presents an estimate of the nature and extent of <br /> <br />probable future floods which can be reasonably expected along the studied channel. <br /> <br />Authorization <br /> <br />The 100-year flood plain is shown on the Flood Hazard Area Delineation Sheets, which <br /> <br /> <br />illustrate the areas that would be inundated by such an event. Flood profiles show the water <br /> <br /> <br />depths relative to the stream bed. The flood profiles and flooded area data presented are <br /> <br /> <br />based upon future, developed conditions in the basin, as determined from current master <br /> <br />planning maps. Possible future improvements to control floods are not a consideration of <br /> <br />this report. <br /> <br />Upon acceptance of this report by the Urban Drainage and Flood Control District, the areas <br /> <br />described as being inundated by the 100-year flood (Intermediate Regional Flood) can be <br /> <br />designatea as flood hazard areas and their - use regulate-d - accordingly. The terms <br /> <br />"Intermediate Regional Flood," "lOO-year flood," and "one percent probability flood" can be <br /> <br />used interchangeably, since they all define the same flood event.- <br /> <br />The information presented herein does not imply any State action to zone or regulate the <br /> <br />use of flood plains. UDFCD has the authority to regulate flood plains, but to date has <br /> <br />chosen to leave flood plain regulation responsibility with local governments. The report <br /> <br />provides a suitable basis for the adoption of land use controls to guide flood plain <br /> <br />management. <br /> <br />This report was authorized by the Urban Drainage and Flood Control District and the City <br /> <br /> <br />of Arvada according to Agreement No. 89-10.10. This agreement included the preparation <br /> <br /> <br />of a Flood Hazard Area Delineation (FHAD). <br /> <br />- <br />Flood water surface elevations and flood plain boundaries are often revised by road and <br /> <br />bridge construction, flood plain development, flood control improvements, or natural <br /> <br />processes. Prior to utilization of this report for planning or design purposes, the user is <br /> <br />-1- <br /> <br />-2- <br />