The Federal Emergency Management Agency (FEMA) is actively involved through the National Flood Insurance Program (NFIP) in a flood mitigation program in Douglas County. The Planning Department of the jurisdiction in which a project is located shall determine if the structure or structures being planned is/are within the 'floodway' or 'floodplain' of a '100 year flood', also known as a 'base flood'.
A 100-year flood event is defined as a flood that has a 1% chance of being equaled or exceeded in any given year. The elevation of the crest of the 'base flood' is referred to as the Base Flood Elevation (BFE). The 'floodplain' is defined as the channel of a river or other watercourse and the adjacent land area that is inundated by the discharge of a base flood. The 'floodway' is defined as that portion of the 'floodplain' which when it is restricted in some manner results in an increase of the elevation of the water's surface of more than one (1 feet to 0 inches) foot (FEMA's criteria) above the base flood elevation (BFE).
When it has been determined by the Planning Department that a parcel of land is encroached upon by the 'floodplain' the services of an engineer or surveyor may be required by the Planning Department in order to provide a pre-construction and post-construction elevation certificate (PDF) for the project.
In order to qualify for the program, FEMA has established that the BFE shall be required to be a minimum of twelve inches (1 foot to 0 inches) below the finished floor elevation of a structure. In the case of manufactured dwellings, the finished floor elevation shall be required to be eighteen inches (1 foot to 6 inches) above the BFE. In the interest of uniformity, the Douglas County Building Department interprets the 'finished floor' elevation to be taken at the structural slab or sheathing (sub-floor) surface of the floor, not necessarily the elevation of the actual finished floor surface. For this interpretation, the actual finished floor surface is that surface established by the installation of the floors finishing surfaces such as carpet, tile, or hardwood flooring.