Doña Ana County, NM Environmental Rules: Flood Zones (2026)

Section 350-604 of the Unified Development Code adopts the effective FEMA Flood Insurance Study for Doña Ana County, along with the accompanying Flood Insurance Rate Maps and Flood Boundary-Floodway Maps, as the legal basis for identifying special flood hazard areas (SFHAs). Subsection C requires a floodplain development permit for any development inside an SFHA, administered through the Flood Commission and reviewed by a Floodplain Administrator the county appoints under subsection B. That review confirms building sites will be reasonably safe from flooding and that all other required federal, state and local approvals, including Clean Water Act Section 404 permits, are in place.

Subsection D adds a three-stage elevation certificate process for any construction in a mapped floodplain: a pre-construction certificate before work begins, an under-construction certificate before the foundation is poured, and a post-construction certificate before a certificate of occupancy issues, each signed and sealed by a New Mexico registered professional surveyor and accepted by the Flood Commission. Under the specific standards in subsection H, new residential construction, substantial improvements, or reconstruction after substantial damage must have the lowest floor, including any basement, elevated to at least one foot above the base flood elevation; nonresidential structures may instead be floodproofed watertight below that line if certified by a registered engineer or architect.

Manufactured homes and enclosed lower areas carry their own anchoring and flood-vent standards elsewhere in the section. These standards apply only to the unincorporated county; Las Cruces, Sunland Park, Mesilla and Hatch run their own floodplain programs.