Butte County, CA Environmental Rules: Flood Elevation Requirements (2026)

" Nonresidential structures may meet that same elevation, or instead be floodproofed watertight below the BFE with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads, certified by a registered professional engineer or architect. In Zone AO, where the map shows a flood depth number rather than a BFE, the lowest floor must sit at least one foot above the highest adjacent grade higher than that depth number, or at least three feet above grade if no depth number is printed on the map.

Unnumbered A Zones without a published BFE use methods comparable to a Flood Insurance Study, or FEMA 265, to fix an equivalent one-foot-above-BFE elevation. Manufactured homes placed or substantially improved in AE, AH or A zones must sit on a permanent foundation with the lowest floor one foot or more above the regulatory flood elevation and be anchored against flotation and lateral movement per FEMA's manufactured-home installation guidance. The county requires a FEMA Form 81-31 Elevation Certificate at three checkpoints: a Construction Drawings Certificate before the building permit issues, a Building Under Construction Certificate before framing inspection approval, and a Finished Construction Certificate before final inspection, all submitted to the Director of Development Services or designee.

The Department of Development Services and Department of Public Works jointly review flood-zone permit applications, and the Director of Public Works or designee is designated the county's floodplain administrator under § 26-20, who must also file a biennial compliance report with FEMA.