Solano County, CA Environmental Rules: Flood Zones (2026)

Chapter 12.2 of the Solano County Code is the Solano County Flood Damage Prevention Ordinance. It defines a Special Flood Hazard Area as land in the floodplain subject to a 1% or greater chance of flooding in any given year (the 100-year floodplain — FEMA zones A, AE, AH, AO, A99, V, VE). When an application is submitted for any building, zoning, use, or grading permit, the Solano County building inspector or Director of Resource Management must determine whether the site is in an SFHA; if so, the application is referred to the County Floodplain Administrator for review. New residential construction in an SFHA must have the lowest floor (including basement) elevated to at least the Base Flood Elevation (BFE), and many parts of unincorporated Solano County also require freeboard above BFE. Non-residential structures may be elevated or dry-floodproofed. The Suisun Marsh, a major SFHA, is additionally regulated under Solano County's component of the Suisun Marsh Local Protection Program. FEMA flood-zone designations also determine whether federally backed mortgages require a flood insurance policy. Owners can check their flood zone through FEMA's Flood Map Service Center or the County's Flood Zone Determination service.