Hercules, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Governing section
- HMC Sec. 10-7.501(c)(1)
- Standard
- Lowest floor at/above base flood elevation
- Certification required
- Registered engineer or licensed surveyor
- Floodplain Administrator
- Director of Public Works
- Violation classification
- Misdemeanor, Sec. 10-7.303
Summary
New and substantially improved homes in Hercules flood hazard zones must have their lowest floor, including basement, elevated to or above the base flood elevation shown on FEMA's flood maps. A registered engineer or surveyor must certify the finished elevation before the Floodplain Administrator signs off.
(c) Elevation and Floodproofing.
(1) Residential Construction. All new construction or substantial improvements of residential structures shall have the lowest floor, including basement:
A. In AE, AH, A1-30 Zones, elevated to or above the base flood elevation.
B. In an AO zone, elevated above the highest adjacent grade to a height equal to or exceeding the depth number specified in feet on the FIRM, or elevated at least two (2) feet above the highest adjacent grade if no depth number is specified.
C. In an A zone, without BFEs specified on the FIRM (unnumbered A Zone), elevated to or above the base flood elevation; as determined under Section 10-7.402(c). Upon the completion of the structure, the elevation of the lowest floor, including basement, shall be certified by a registered civil engineer or licensed land surveyor, and verified by the Community Building Inspector to be properly elevated.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 555, passed March 25, 2025).
Full Breakdown
501(c)(1) of the Hercules Municipal Code, part of Chapter 7's flood hazard reduction standards, requires that all new construction or substantial improvements of residential structures have the lowest floor, including any basement, elevated to or above the base flood elevation (BFE) in AE, AH, and A1-30 zones. In an AO zone, the floor must sit above the highest adjacent grade by the depth number shown on the Flood Insurance Rate Map, or at least two feet above grade if no depth number is specified. 402(c) using FEMA guidance such as FEMA 265.
Once built, a registered civil engineer or licensed land surveyor must certify the as-built elevation of the lowest floor, and the Community Building Inspector verifies the structure was properly elevated before the certification goes to the Floodplain Administrator. 501(c)(2): floodproof the building watertight below the elevation required for residential construction instead of physically raising it, with structural components able to resist hydrostatic and hydrodynamic loads. 302 and kept on file at City Hall, 111 Civic Drive.
Violations & Fines
Section 10-7.303 makes violation of the flood damage prevention chapter, including construction below the required elevation, a misdemeanor, and the City Council can pursue any other lawful action to prevent or remedy the violation. Under the definitions in Section 10-7.102, a structure lacking the required elevation certificate or other compliance documentation is presumed to be in violation until that documentation is produced.
Frequently Asked Questions
How high must a new house be built in a Hercules flood zone?
What if my Hercules lot is in an AO zone with no depth number on the FIRM?
Who certifies that a building was elevated correctly in Hercules?
Sources & Official References
Other rules in Hercules
California rules heatmap·Compare Hercules to another location·View the California environmental rules overview
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Flood Elevation Requirements in Nearby Cities
How other cities in Contra Costa County handle flood elevation requirements.