"See 44 C.F.R. ?? 60.5(b)(2) (imposing the condition that certain communities ???[r]equire a setback for all new development from the ocean, lake, bay, riverfront or other body of water, ... designated by the Administrator according to the flood-related erosion hazard and erosion rate, ... and depending upon the geologic, hydrologic, topographic and climatic characteristics of the community's land," . . . .