Flood Zones: Rialto vs San Bernardino
How do flood zones rules compare between Rialto, CA and San Bernardino, CA?
Rialto has fewer restrictions than San Bernardino.
Rialto, CA
San Bernardino County
Rialto participates in the National Flood Insurance Program (NFIP, CID 060274) and enforces FEMA floodplain construction standards. Most of the developed city is in Zone X (minimal flood risk), but portions along the Cactus Basin, Lytle Creek wash, and tributaries of the Santa Ana River carry Zone A / Zone AE Special Flood Hazard Area designations under the San Bernardino County FIRM panels effective August 28, 2008. Construction in SFHAs requires elevation to or above base flood elevation (BFE) and a floodplain development permit.
View full Rialto rules →San Bernardino, CA
San Bernardino County
San Bernardino participates in the NFIP and regulates development in FEMA flood zones. Structures in Zone A or AE must meet base flood elevation standards; floodplain permits required.
View full San Bernardino rules →Key Facts Comparison
| Fact | Rialto | San Bernardino |
|---|---|---|
| NFIP Community ID | 060274 (City of Rialto) | - |
| FIRM effective date | August 28, 2008 (San Bernardino County) | - |
| Primary flood zones | Zone X citywide; Zone A/AE along Lytle Creek, Cactus Basin | - |
| Elevation standard | Lowest floor at or above Base Flood Elevation | - |
| Substantial improvement | ≥50% of market value triggers full SFHA compliance | - |
| NFIP Participation | - | Active NFIP community |
| Key Flood Areas | - | Santa Ana River, Warm Creek, City Creek |
| Freeboard Required | - | BFE plus 1 foot |
| Substantial Improvement | - | 50% of structure value |
| Regional Agency | - | SB County Flood Control District |
Highlighted rows indicate differences between cities.
Rialto FAQ
How do I find my flood zone in Rialto?
Use the FEMA Map Service Center (msc.fema.gov) and search your address. The official FIRM for Rialto is part of the San Bernardino County panel set effective August 28, 2008. The city can also provide a free flood zone determination.
Do I need flood insurance in Rialto?
If your property is in Zone A or AE and you have a federally backed mortgage, flood insurance is mandatory under 42 U.S.C. §4012a. In Zone X it is optional but strongly recommended near washes and basins.
Can I build an addition in a flood zone?
Yes with a floodplain development permit, provided the addition meets BFE elevation or dry-floodproofing standards. If the project value is ≥50% of the structure's market value, the entire building must be brought into SFHA compliance.
San Bernardino FAQ
How do I check if my San Bernardino property is in a flood zone?
Use the FEMA Flood Map Service Center at msc.fema.gov and enter your address. San Bernardino Community Development staff can also confirm your zone and any local floodplain overlays at (909) 384-5122.
Do I need flood insurance in San Bernardino?
Properties in Zones A, AE, or AO with federally backed mortgages require flood insurance. Homeowners in Zone X can purchase Preferred Risk Policies at lower cost. Alluvial fan and debris flow areas in the foothills have significant risk even outside mapped zones.
Compare other topics
See how Rialto and San Bernardino compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool