Calvert County, MD Environmental Rules: Flood Elevation Requirements (2026)

Chapter 46 defines the Flood Protection Elevation as the base flood elevation, the one-hundred-year flood level shown on FEMA's Flood Insurance Study, plus one foot of freeboard added for safety against calculation error, wave action and settlement (§ 46-5). Section 46-21 then makes that elevation the mandatory floor: every new or substantially improved residential and nonresidential structure in a nontidal or tidal floodplain must have its lowest floor, including any horizontal footprint expansion that is less than a substantial improvement, built at or above the flood protection elevation, and basements are not permitted anywhere in the floodplain.

A registered surveyor or professional engineer must certify the as-built lowest floor elevation on a FEMA elevation certificate before the county will issue a certificate of occupancy, and work done before that certification is at the applicant's own risk (§ 46-7D). In the coastal high-hazard V Zone the standard is stricter still: structures must sit on pilings or columns with the lowest horizontal structural member at or above the flood protection elevation, slab foundations are prohibited, and any enclosed space below that elevation may only be used for parking, storage or building access under a signed nonconversion agreement (§§ 46-26, 46-33).

Accessory structures and attached or detached garages get narrow, size-based exemptions from full elevation, up to 300 square feet by right and up to 600 square feet with a conditioned permit, but anything larger must meet the same flood protection elevation or obtain a variance from the Board of Appeals (§§ 46-10, 46-37, 46-40).