Clarkstown, NY Environmental Rules: Flood Elevation Requirements (2026)

Town Code Chapter 146, the Town's floodplain management law, sets the elevation floor for building in any area of special flood hazard shown on the Flood Insurance Rate Map adopted at § 146-4B. Under § 146-6C(1)(a), new construction and substantial improvements to residential structures must have the lowest floor, including the basement, elevated to or above two feet above the base flood elevation (BFE), that is, two feet of freeboard above the FEMA-mapped flood level. Where a Zone A parcel has no published BFE, § 146-6C(1)(b) requires the applicant either to obtain federal, state or other data and add two feet of freeboard, or to have a registered design professional determine the BFE using accepted hydrologic and hydraulic engineering practices, plus freeboard, with studies submitted in enough detail for the local administrator to review.

In Zone AO, the lowest floor must sit above the highest adjacent grade at least as high as the FIRM's depth number plus two feet, or three feet if no depth number is shown. Nonresidential structures under § 146-6D(1) must either meet the same two-foot-above-BFE elevation or be floodproofed watertight below that line, with attendant utility and sanitary facilities protected and structural components able to resist hydrostatic and hydrodynamic loads. Accessory structures, including detached garages, follow § 146-6F: portions below BFE plus two feet must use flood-resistant materials, and mechanical/utility equipment must be elevated or dry floodproofed to that same line.

Manufactured homes under § 146-6E(2) must have the chassis frame elevated to or above two feet above the BFE. The local administrator reviews all applications against § 146-6 before issuing a permit, and a proposed development that fails these standards or would cause physical damage to other property cannot be permitted as submitted.