Boone County, IN Environmental Rules: Flood Zones (2026)

Boone County Code Chapter 152 governs development in the Special Flood Hazard Area (SFHA) in unincorporated Boone County, Indiana. Section 152.12 requires a floodplain development permit before the commencement of any development activity in the SFHA, and § 152.13 bars locating, extending, converting or structurally altering any structure there without full compliance with the chapter. The building protection requirement of § 152.36(A) reaches new structures over 400 square feet, additions or improvements costing 50% or more of the structure's value, repairs to a damaged structure costing 50% or more of its pre-damage market value, a manufactured home placed on a new site, and a travel trailer or recreational vehicle installed on a site for more than 180 days.

Under § 152.36(B), new or substantially improved residential structures, including manufactured homes, must have their lowest floor, including any basement, at or above the flood protection grade, defined as two feet above the base flood elevation. Non-residential structures may instead be floodproofed to that grade if a registered professional engineer or architect certifies the design under § 152.36(C). Recreational vehicles left on a site beyond 180 days must either be elevated and anchored like a manufactured home or remain fully licensed and ready for highway use under § 152.36(F)(5).

Fill placed under a structure must be compensated with an equivalent volume of excavation in the floodplain under § 152.35(K). Construction inside an identified floodway additionally needs a permit from the Indiana Department of Natural Resources under § 152.39 before the county issues a building permit. The Floodplain Administrator and Boone County Area Plan Commission administer these standards, and § 152.99 makes noncompliance a common nuisance.