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Fooodplain Delineation Report <br />Hogue Pit Page 1 of 3 <br />PURPOSE AND SCOPE <br />The purpose of this study is to provide a delineation of the 100-year flood-plain and flood- <br />way and determine base flood elevations for the reach of the Yampa River adjacent to the <br />Hogue aggregate mining facility. The subject reach is approximately four miles downstream <br />of the Steamboat Springs, Colorado (Figure 1). <br />A site specific floodplain and floodway delineation was requested by the Routt County <br />Planning Department in a letter dated January 10, 2002. The request was made by the <br />County as a portion of extending a Special Use Permit for operation of the facility. The site <br />specific study was required partially because FEMA had not determined Base Flood <br />Elevations within this reach. <br />The scope of this study is specific to delineating the floodplain and floodway and determining <br />the base flood elevation for 2,700 feet of River immediately adjacent to the Hogue aggregate <br />mine. <br />SITE DESCRIPTION <br />The Hogue Pit reach of the Yampa River is virtually straight with a low gradient. The channel <br />is generally a single thread channel with a well defined thalweg. Bluffs dominate the left <br />descending bank whereas the right descending bank consists of moderately high banks and <br />broad overbank floodplains. Moderate stands of riparian and shrub /scrub vegetation are <br />growing along the banks. The right overbank areas are pasture grasses or the existing <br />aggregate operation. Several small areas of wetlands and willows exist adjacent to the river. <br />SOURCE OF DATA <br />Cross-section and elevation data were field surveyed by Emerald Mountain Surveys, Inc. <br />Cross-sections were field located by Paul C. Currier, P.E. of Water Resource Consultants, <br />LLC on February 6, 2002. A total of 18-24 inches of snow was on the ground at the time of <br />the survey. However, much of the river was ice-free, which allowed for accurate surveying of <br />the river. Likewise, the snow did not hinder acquisition of accurate ground data. Survey <br />data of this nature is considered accurate to less than 0.1 feet. <br />wN~raswwes ovm~.rwr+n.uc <br />G-1 <br />