Lancaster City Council adopted floodplain regulations with passage of the Flood Damage Prevention Ordinance, Chapter 1331 of the Codified Ordinances of the City of Lancaster, Ohio, in 1979 that became effective in 1980. The ordinance was revised in 2011 as part of the Flood Map Modernization program.
Under Chapter 1331, City Council has established the Certified Building Department as the Administrator of the floodplain regulations. They are responsible for all aspects of the Development Permit Process and for maintaining the required National Flood Insurance Program information.
For regulatory purposes, the floodplain is divided into two areas based on water velocity: the floodway and the flood fringe. The floodway includes the channel and adjacent floodplain area that is required to pass the 100-year flood without unduly increasing flood heights. This is the hazardous portion of the floodplain where the fastest flow of water occurs. Due to the high degree of hazard found in the floodway, floodplain regulations require that proposed floodway developments do not block the free flow of flood water as this could dangerously increase the water's depth and velocity. The flood fringe is the portion of the floodplain, outside of the floodway, that contains slow-moving or standing water. Development in the fringe will not normally interfere with the flow of water. Therefore, floodplain regulations for the flood fringe allow development to occur but require protection from flood waters through the elevation of buildings above the 100-year flood level or floodproofing buildings so that flood water cannot enter the structure.