St. Louis County, MN Environmental Rules: Flood Elevation Requirements (2026)

Section 2.141 of Floodplain Ordinance 69 defines the Regulatory Flood Protection Elevation (RFPE) as an elevation one foot above the base flood elevation, plus any increase in water surface elevation caused by encroachments on the floodplain that result from designating a floodway; those increases are identified in the Floodway Data Tables of the Flood Insurance Study. The one-foot freeboard applies wherever the RFPE governs a construction standard.

Section 6.21.A applies the RFPE to residential construction in the Flood Fringe District: a structure erected, reconstructed, altered, or moved on fill must have its lowest floor, as defined in Section 2.135, elevated at or above the RFPE, with the finished fill elevation at or above the base flood elevation plus any floodway-related stage increase. The fill must extend at the same elevation at least 15 feet beyond the structure's outside limits, and the elevation must be certified by a registered professional engineer, land surveyor, or other qualified person the Director designates. A residential structure that cannot meet the fill standard needs a Conditional Use Permit under Section 6.31 to use an alternative elevation method instead. Section 6.22 applies a parallel but less strict rule to nonresidential structures: they may be elevated on fill without the 15-foot extension requirement, dry-floodproofed watertight up to the RFPE, or elevated using alternative methods, while heating, ventilation, and utility equipment must sit at or above the RFPE under Section 4.21.D regardless of building type.