Grand Junction, CO Environmental Rules: Flood Elevation Requirements (2026)

Grand Junction Municipal Code § 21.06.020(c)(2) starts from a compliance baseline: no structure may be constructed, located, extended, converted, or altered without full compliance with the flood damage protection section, and no land may be developed without it. Under § 21.06.020(d)(2)(i), new construction or substantial improvement of a residential structure in a mapped special flood hazard area must have its lowest floor, including any basement, elevated at least one foot above the base flood elevation (BFE), the standard drawn from FEMA's Flood Insurance Study for Mesa County and Incorporated Areas dated October 16, 2012, and the associated Flood Insurance Rate Maps adopted by reference.

Commercial, industrial, or other nonresidential structures get an alternative path: they may either meet that same one-foot-above-BFE elevation, or be flood-proofed so the structure is watertight below the BFE, with walls substantially impermeable to water, structural components able to resist hydrostatic and hydrodynamic loads, and the whole design certified by a Colorado registered professional engineer, whose certification is reviewed by the Director. A separate one-foot freeboard rule applies to properties removed from the floodplain by a FEMA Letter of Map Revision Based on Fill: a Floodplain Development Permit will not issue for new construction there if the lowest floor sits below the base flood elevation with one foot of freeboard that existed before the fill was placed.