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Floodplain Delineation Report Hogue Pit 1 of 4 PURPOSE AND SCOPE The purpose of this study is to provide a delineation of the 900-year flood-plain and flood- way and determine base hood elevations for the reach of the Yampa River adjacent fo the Hogue aggregate mining facility. The subject reach is approximately four miles downstream of the Steamboat Springs, Colorado (Figure 1). A site specific floodplain and floodway delineation was requested by the Routt County Planning Department in a letter dated January 10, 2002. The request was made by the County as a portion of extending a Special Use Permit for operation of the facility. The site specific study was required partially because FEMA had not determined Base Flood Elevations within this reach, The scope of this study is specific to delineating the floodplain and floodway and determining the base flood elevation for 2,700 feet of River immediately adjacent to the Hogue aggregate mine. SITE DESCRIPTION The Hogue Pit reach of the Yampa River is virtually straight with a low gradient. The channel is generally a single thread channel with a well defined thalweg. 81uffs dominate the left descending bank whereas the right descending bank consists of moderately high banks and broad overbank floodplains. Moderate stands of riparian and shrub /scrub vegetation are growing along the banks. The right overbank areas are pasture grasses or the existing aggregate operation. Several small areas of wetlands and willows exist adjacent to the river. SOURCE OF DATA Cross-section and elevation data were field surveyed by Emerald Mountain Surveys, Inc. Cross-sections were field located by Paul C. Currier, P.E. of Water Resource Consultants, LLCon February 6, 2002. A total of 18-24 inches of snow was on the ground at the time of the survey. However, much of the river was ice-free, which allowed for accurate surveying of Rec I -- 17 :Mac-02 WATER RE6OURCE CONSVLTARTS. LLC ~~r