The regulatory floodplain shall be those areas of Calvert County which are subject to the one-hundred-year flood, delineated on the most recent revision of the community's Flood Insurance Rate Maps (FIRM) and described in the Flood Insurance Study (FIS) prepared by the Federal Emergency Management Agency (FEMA). FIRM maps and the FIS, if available for the community, must be used. Areas along nontidal streams that do not have FEMA delineations as described above are subject to regulation by this chapter and the state.
A community may have one or more of the following Floodplain Zones:
A. 
Nontidal floodplains consist of the floodway and the floodway fringe. Nontidal floodplains may have detailed engineering study data, profiles and water surface elevations, or may have approximate delineations only.
B. 
Tidal floodplains consist of areas subject to coastal or tidal flooding by the one-hundred-year flood. These areas are flooded due to high tides, hurricanes, tropical storms and steady on-shore winds.
C. 
Coastal high-hazard areas consist of areas subject to coastal or tidal flooding with the addition of high velocity water and wind action. These areas are designated as V Zones on the Flood Insurance Rate Maps.
A. 
Floodplain zone determination. The local permitting official will determine the Floodplain Zone in which the development activity is proposed using, at minimum, the FIS and FIRM, and also will use mixed alluvial soils ("My soils") as shown on the USDA soils maps, and/or elevation. Without prior approval from FEMA, the community shall use no other data to enforce floodplain management regulations. Where map boundaries and elevations disagree, elevations prevail, with no approval from FEMA required.
B. 
Approximate floodplain determination. For development proposed in the approximate floodplain (no water surface elevations provided), the applicant must use the best available information to determine the elevation of the one-hundred-year flood, and must delineate this on the site plan submitted for approval. For new subdivisions, the applicant must have the one-hundred-year flood elevations certified by a registered professional engineer based on hydrologic and hydraulic analyses which include a floodway analysis. For individual lot development, if no data are available, the point-on-the-boundary method may be used. In this method, the distance is scaled from a reference point at the site to the edge of the one-hundred-year floodplain boundary indicated on the FIRM. An elevation of the one-hundred-year flood is determined at that point by survey. Mixed alluvial ("My") soils and base flood elevations of adjacent floodplains may also be used.