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<br />is estimated by utilizing the regression equation for Arkansas River Basin Subregion Ark-6, Quo <br />= 45.98 * (A)O.717, where QlOO is the 100-year peak flow in cubic feet per second and A is the <br />upstream (contributing) drainage area in square miles; and <br /> <br />WHEREAS, the drainage basin for that portion of Grape Creek which extends <br />downstream from the USGS stream gage just downstream of Westcliffe to the Custer'County line <br />exceeds the upper limit, 330 square miles, for Arkansas River Basin Subregion Ark-6, as set <br />forth in the Guidelinesfor Determining IOO-Year Flood Flows for Approximate Floodplains; <br />and <br /> <br />WHEREAS, the 100-year flow for Hardscrabble Creek downstream of its confluence with <br />South Hardscrabble Creek and Low Back Creek are estimated by utilizing the regression equation <br />for Arkansas River Basin Subregion Ark-3, QlOO = 1,089.27 * (A)o.635, where QlOO is the 100-year <br />peak flow in cubic feet per second and A is the upstream (contributing) drainage area in square <br />miles; and <br /> <br />WHEREAS, a procedure for determining hydrology information in Custer County for <br />approximate floodplains of streams with drainage areas that fall outside of the regression criteria, <br />lakes, ponds, and local drainage areas has not been established by the Guidelines for <br />Determining lOO-year Flows for Approxinwte Floodplains; and <br /> <br />WHEREAS, the streams with drainage areas that fall outside the regression criteria, lakes, <br />ponds, and local drainage areas may be designated as approximate floodplain ipformation without <br />a procedure for estimating 100-year peak flows, as long as the local government understands and <br />agrees that a detailed hydrologic and hydraulic study is required prior to any floodplain <br />development; and <br /> <br />WHEREAS, Custer County, Colorado, has requested the Colorado Water Conservation <br />Board to designate and approve the floodplains set forth in the aforesaid new report; and <br /> <br />WHEREAS, Section 37-60-106(1)(c), Colorado Revised Statutes, requires the Colorado <br />Water Conservation Board to assist in the prevention of floods and flood damages therefrom; and <br /> <br />WHEREAS, Sections 31-23-301 and 30-28-111, Colorado Revised Statutes, provide that <br />legislative bodies of local jurisdictions may provide zoning regulations for land uses on or along <br />any storm or floodwater runoff channel or basin only after designation and approval by the <br />Colorado Water Conservation Board; and <br /> <br />WHEREAS, Section 37-60-l06(1)(c), Colorado Revised Statutes, directs the Colorado <br />Water Conservation Board to designate and approve storm or floodwater runoff channels or <br />basins and to make such designations available to legislative bodies of local jurisdictions; and <br /> <br />WHEREAS, the information in said new report with included mapping for said stream <br /> <br />4 <br />