FEMA requires 3 feet of freeboard for levees, but is their a freeboard requirement for culverts? A developer wants to build adjacent to a creek that goes underground through a culvert for 50 feet. If, for example, the hydraulic analysis shows the water surface elevation at the upstream end of culvert is at elevation of 100 feet, at what elevation must the finish floors be? This is not a levee situation. The effective map shows this area as an A zone, so we are having the developer do the hydraulic analysis to determine a BFE.