The Contra Costa County Floodplain Management Program is for unincorporated County areas only, and provides floodplain information for existing structures and proposed projects.
In July 1987, the Federal Emergency Management Agency (FEMA) produced a Flood Insurance Study (FIS) and printed Flood Insurance Rate Maps (FIRMs). These watersheds are re-studied and re-mapped periodically, showing areas with a one percent chance of flooding each year. These areas are commonly referred to as "100-year floodplains," and are shown as Special Flood Hazard Areas (SFHAs) on the FIRM maps. Flood insurance is mandatory for residential, commercial, and industrial developments within SFHAs.
In compliance with the National Flood Insurance Program (NFIP), Contra Costa County adopted a Floodplain Management Ordinance. This Ordinance requires that the lowest floor, including basement, for all new structures or substantial improvements to existing structures within a SFHA, shall be elevated one to two feet above the 100-year Base Flood Elevation (BFE) for that area. Lower insurance rates are available when the lowest floor is above the BFE.