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<br />WHEREAS, Section 37-60-106(1)(c), Colorado Revised Statutes, directs the Colorado Water
<br />Conservation Board to designate and approve storm or floodwater runoff channels or basins and to
<br />make such designations available to legislative bodies oflocal jurisdictions; and
<br />
<br />CONSISTENCY WITH PREVIOUS FLOODPLAIN STUDIES
<br />
<br />WHEREAS, the detailed floodplain information for South Platte River revises and is, therefore,
<br />inconsistent with the detailed and approximate floodplain information for South Platte River contained
<br />in Resolutions No.1, 84, 119, 150, 153,251,327,328,329,379,354.03,484, and 530; and
<br />
<br />WHEREAS, all Letters of Map Amendments (LOMA's), Letters of Map Revisions Based on
<br />Fill (LOMR-F's), and Letters of Map Revisions (LOMR's) approved by FEMA prior to April, 2005
<br />but not designated by the CWCB were based on floodplain information superseded by, and therefore
<br />inconsistent with, the new report dated April, 2005 for Adams County, the City of Brighton, the City of
<br />Thornton, and the City of Commerce City; and .
<br />
<br />COMPLIANCE WITH CWCB TECHNICAL STANDARDS
<br />
<br />WHEREAS, said new report is based on conversion of the 2002 South Platte River in Adams
<br />County Master Plan Update, U.S. Army Corps of Engineers HEC-2 hydraulic model to the U.S. Army
<br />Corps of Engineers HEC-RAS hydraulic model, Version 3.1.1, for the 10-, 50-, and 100 year flood
<br />frequencies and is inconsistent with the hydraulic infonnation that was used as the basis of all previous
<br />detailed floodplain information for South Platte River in Adams County, the City of Brighton, the City
<br />of Thornton, and the City of Commerce City; and
<br />
<br />WHEREAS, said new report determined the 500-year flood frequency and incorporated the
<br />500-year flood discharge into the U.S. Army Corps of Engineers HEC-RAS hydraulic model, Version
<br />3. 1.1; and
<br />
<br />WHEREAS, LOMRs and other changes were incorporated into the new study; and
<br />
<br />WHEREAS, floodway limits for the 100-year flood frequency assuming both a 1 ft maximum
<br />rise, as defined by FEMA, and a 0.5 ft maximum rise, as defined by UDFCD and Adams County, were
<br />computed for said new report using the U.S. Army Corps of Engineers HEC-RAS hydraulic model,
<br />Version 3.1.1,; and
<br />
<br />WHEREAS, the detailed 100-year floodplain and floodway information for South Platte River
<br />in said new report meets the requirements listed under the Board's "Rules and Regulations for
<br />Regulatory Floodplains in Colorado" (2 CCR 408-1); and
<br />
<br />WHEREAS, Adams County, the City of Brighton, the City of Thornton, the City of
<br />Commerce City, and the Urban Drainage and Flood Control District should continue to regulate new
<br />development and construction in floodplain areas on a case-by-case basis based on the information
<br />
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