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Engineers (USAGE) in October 1963. Tire report, "Flood Plain Information, Metropolitan Region, Denver, Colorado, South Platte River, Waterton to Brighton, Colorado", is based on hydrology which is considered outdated and does not consider development change; o:hich have taken place within the study reach since its publication. These changes include new channel allignment, reconstruction of Henderson Road and bridge, construction of several levees and ur- banization upstream. Base hydrology data for this study included widely spaced field surveyed cross sections, and base mapping enlarged from USGS 7;, gradrat~gle maps. even through the study remains the official flood plain designateu by the Colorado Wa;:er Conservatior. Board, the data were not used to identify the 100-year flood plain on the mining site. A more recent study has been undertaken by the Federal Insurance Administration (FIA) This study was based on more up-to-date hydrology and included some important changes like the reconstruction of Henderson Road and bridge. The level of detail for this study is consistcntonly with its purpose, which is the establishment of flood-insurance rate maps. Base hydrologic data include the 1963 Corps of En- gineers surveyed cress-sections, supplemented by a few additional cross-sections at key locations, and base mapping enlarged from USGS 71~ minute quadrangle maps. Although the study has not been officially released, it contains the most recent hydrologic information. Prelim- inary hydraulic information including flooa plain elevations, depths and velocities, and floudway data was obtained to help with this analysis. .The Urban Drainage and Flood Conti:ol District (UDFCD) is in the process of preparing a flood hazard area delinea- tion study for the area. It will include further refinement of the flood hydrology and detailed topographic mapping. Mapping having a scale of 1 inch to 200 feet and a contor interval of 2 feet was obtained from the UDFCD. No hydraulic calculations are presently available from this study. The flood profile from the F-,. tudy was plotted on the detailed 1 inch to 200 feet topographic mapping of the UDFCD study (Plates I,ZI, and III). Analysis of the flooded limits reveals one major inconsistancy: a levee on the west bank of the South Platte River separates flow on the left overbank from flow in the channel for a considerable reach in the mining site. The separates:: of lows would indicate that flooding on the overbank may act independently o.. the flow in the channel. Amore de~ailed analysis would be required to establish precisely t'.~e food characteristics on the left overbank, which affects t.re site most directly. On May 5, 1973, a significant flood tray e:q:erienced on tlae South Platte River. Tiie flood event approximated the I00-year peak discharge. The peak discharge was estimated ~5-