Coon Rapids, MN Environmental Rules: Flood Elevation Requirements (2026)

The regulatory flood protection elevation, defined in Section 11-1101.2(4), is never lower than two feet above the elevation of the regional (one percent annual chance) flood, plus any rise caused by floodway encroachments. That two-foot freeboard applies citywide across the Floodway, Flood Fringe, and General Floodplain Districts. In the Flood Fringe District, Section 11-1101.5(2)(a) requires the lowest floor of every structure, including accessory buildings, to sit at or above the RFPE on compacted fill, with the finished fill elevation no more than one foot below the RFPE and extending at least 15 feet beyond the building's outside limits.

All service utilities, including ductwork, must be elevated or watertight. An accessory structure of 576 square feet or less can skip elevation and instead be internally floodproofed to the FP-3 or FP-4 classifications of the State Building Code under Section 11-1101.4(4)(c), with automatic flood-venting openings sized at one square inch per square foot of enclosed area. In the Floodway District itself, Section 11-1101.4(4)(c)(iii) requires accessory structures to be elevated on fill or dry-floodproofed to the FP-1 or FP-2 classification, with mechanical and utility equipment raised to or above the RFPE.

Residential basements are barred below the RFPE in the Flood Fringe District under Section 11-1101.5(4)(b), and nonresidential basements below that line must be structurally dry floodproofed under Section 11-1101.5(4)(c). As-built fill and floodproofing elevations must be certified by a registered professional engineer, architect, or land surveyor under Section 11-1101.10(2)(d), and the Director keeps a permanent record of every structure's lowest-floor elevation.