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

Alameda County Code § 17.30.090 requires that any structure permitted in a combining FF (flood fringe) district have its lowest floor, including any basement floor, at least one foot above the level of the adopted 100-year flood for that area: effectively a one-foot freeboard requirement layered onto the underlying zoning district. Facilities serving those structures, like waste treatment, water supply or sanitary transportation systems, must use flood-proofing techniques matched to the local flood hazard. This standard applies only where the county has combined the FF designation with the underlying district in unincorporated territory such as Castro Valley or San Lorenzo; it does not reach Oakland, Berkeley or the county's incorporated cities.