Flood inundation polygons for the 50-year flood, for Rio Pelo, El Progreso, Honduras. Water-surface elevations for an estimated 50-year-flood discharge on Rio Pelo at El Progreso were determined using HEC-RAS, a one-dimensional step-backwater computer program. The channel and floodplain cross section geometry used in HEC-RAS were developed from an airborne light detection and ranging (LIDAR) topographic survey of the area. The 50-year-flood discharge for Rio Pelo, 235 cubic meters per second, was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The area of inundation and depth of flood coverage was created with the HEC-RAS output and topographic TIN using HEC-geo-RAS software.