Ontario, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard minimum
- 1 ft above base flood elevation
- Zone AH/AO minimum
- 1-2 ft above FIRM depth number
- Permit required
- Development permit, Floodplain Administrator
- Administrator
- City Development Director
- Certification
- Registered engineer or surveyor
- Violation
- Misdemeanor under Sec. 8-13.303
Summary
In Ontario's special flood hazard areas, new construction and substantial improvements must have the lowest habitable floor built at least one foot above the base flood elevation. A development permit from the Floodplain Administrator is required before any building or grading begins there.
New construction and substantial improvements of any structure shall have the lowest habitable floor, including basement, elevated to at least one (1) foot above the base flood elevation. Nonresidential structures may meet the standards in § 8-13.501(c)(3). Upon the completion of the structure, the elevation of the lowest floor, including basement, shall be certified by a registered professional engineer or surveyor, or verified by the community building inspector to be properly elevated. Such certification or verification shall be provided to the Building Official.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-32: Current through Ordinance 3338, passed 7-21-2026).
Full Breakdown
Ontario Municipal Code Chapter 8-13 implements the National Flood Insurance Program locally. 201(g) defines as the elevation of the base (100-year) flood relative to the datum shown on the Flood Insurance Rate Map. 501(c)(2) instead requires the lowest floor at least one foot above the FIRM-listed depth number, or two feet if none is specified. Upon completion, a registered professional engineer or surveyor must certify the as-built lowest-floor elevation to the Building Official. 501(c)(3), watertight to one foot above BFE and certified by a licensed engineer or architect to the Floodplain Administrator.
401 requires a development permit, with plans showing proposed elevations, floodproofing elevation, required certifications, and any watercourse alteration. 402. 504, plus anchoring to a permanent foundation. 602, and are barred outright inside a designated floodway if they would raise flood levels; any variance granted must be recorded against the property's chain of title with the San Bernardino County Recorder.
Violations & Fines
Section 8-13.303 makes any construction or land alteration in a special flood hazard area that fails to comply with Chapter 8-13, including violation of permit conditions, a misdemeanor. The City Council retains authority to take any lawful action necessary to prevent or remedy a violation, and the ordinance's minimum standards are liberally construed in favor of the City under Section 8-13.305.
Frequently Asked Questions
How high above flood level must a new house be built in Ontario?
Do I need a permit before building in a flood zone in Ontario?
Can a non-residential building floodproof instead of elevating?
What happens if a structure is built below the required elevation?
Sources & Official References
Other rules in Ontario
California rules heatmap·Compare Ontario to another location·View the California environmental rules overview
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Flood Elevation Requirements in Nearby Cities
How other cities in San Bernardino County handle flood elevation requirements.