Bernalillo County, NM Environmental Rules: Flood Elevation Requirements (2026)

Bernalillo County Code § 38-102 sets the specific construction standards that apply once base flood elevation data exists for a site. Subsection (1) requires new construction and substantial improvements to any residential structure to have the lowest floor, including the basement and all attendant utilities and ductwork, elevated to one foot or more above the base flood elevation, the one-foot margin New Mexico floodplain managers call freeboard. Subsection (2) gives commercial, industrial and other nonresidential buildings a choice: match that same one-foot freeboard, or floodproof the structure below the base flood level so walls stay substantially watertight and can resist hydrostatic and hydrodynamic loads, with a registered professional engineer certifying the design.

Subsection (3) covers enclosed areas built below the lowest floor, such as crawl spaces: they must be engineered, or built with at least two openings on separate walls providing one square inch of net area for every square foot of enclosed floor space, with the bottom of each opening no higher than one foot above grade, so floodwater can enter and exit instead of pressurizing the walls. "Base flood elevation" itself is defined at § 38-32 as the water surface elevation shown on the FEMA Flood Insurance Rate Map for the county's flood zones, the elevation with a one percent chance of being equaled or exceeded in any given year.

The county floodplain administrator verifies compliance when reviewing the development permit required under § 38-72, and a structure that lacks the required elevation certificate is presumed to be in violation under the article's definitions section.