Acalanes Ridge Environmental Rules: Flood Zones Rules (2026)

Contra Costa County participates in FEMA's National Flood Insurance Program (NFIP) and enforces floodplain management standards through Ordinance Code Chapter 914-14 (Flood Hazard Reduction). Special Flood Hazard Areas (SFHAs) mapped as Zone AE, A, and VE appear on FEMA Flood Insurance Rate Maps (FIRMs) with significant extent along the Sacramento-San Joaquin Delta (Bethel Island, Byron, Knightsen), Suisun Bay shoreline (Bay Point, Pittsburg, Martinez), San Pablo Bay (Rodeo, Crockett), and along creeks throughout the County (Walnut Creek, Marsh Creek, San Pablo Creek, Pinole Creek). New construction and substantial improvements (repairs or additions costing 50 percent or more of pre-improvement market value) within the SFHA must have the lowest floor elevated to or above the Base Flood Elevation (BFE) shown on FIRMs. Non-residential structures may alternatively be dry-floodproofed. Bethel Island has particularly complex levee-protected floodplain issues. All development in the floodplain requires a floodplain development permit. FEMA CRS (Community Rating System) discounts may apply to flood insurance premiums. Elevation certificates are required. Properties near levees are increasingly scrutinized following Hurricane Katrina and central-valley levee standards. Mortgage lenders require flood insurance for federally backed loans in SFHAs.