A topographic survey depicts the topography or the “lay of the land” of a specific parcel(s). Elevations are taken with surveying equipment at several points on the property and plotted on paper. Contours are drawn to connect identical points of elevation. Contour lines are shown as assumed datum or in USGS datum.
When is a topographic survey in USGS datum required?
Projects proposed to be constructed or located in a floodplain or in a mapped floodplain are required to have topographic survey data in USGS datum. USGS datum allows the elevations mapped on the property to be coordinated with elevations for lakes, streams, and floodplains.