Lincoln County, SD Environmental Rules: Flood Elevation Requirements (2026)

Lincoln County Code § 153.066(A) requires new construction and substantial improvement of any residential structure in a flood hazard area to have the lowest floor, including any basement, elevated to at least two feet above the base flood elevation (BFE), giving the county a two-foot freeboard margin above FEMA's mapped flood level. Properties that received a letter of map amendment or letter of map revision based on fill must have the lowest structure opening elevated to that same two feet above BFE and must otherwise conform to this section and FEMA/FIA Technical Bulletin 10-01.

A registered professional engineer, architect, or land surveyor must certify to the county's Floodplain Administrator that the elevation standard has been satisfied. Non-residential buildings under § 153.066(B) face the same two-foot elevation choice, or may instead be floodproofed watertight below that height. The county's § 153.012 definitions describe FREEBOARD as a safety factor, expressed in feet above a flood level, meant to compensate for unknown factors such as bridge or culvert openings and watershed urbanization that can push flood heights above the calculated level, and BASE FLOOD ELEVATION as the surface elevation of the 1% annual chance flood referenced to the North American Vertical Datum (NAVD 88) shown on the county's FIRM.

The related general standard at § 153.065(C) separately requires that any new construction or substantial improvement built below two feet above BFE use flood-damage-resistant materials, and § 153.065(D) requires electrical and mechanical equipment kept at least one foot above BFE.