Honolulu County, HI Environmental Rules: Flood Zones (2026)
FEMA flood zone rules in Honolulu County, HI, also called floodplain regulations or special flood hazard area (SFHA) rules, determine flood insurance requirements and elevation standards for new construction.
Key Facts
- Governing provision
- ROH § 21A-1.10
- Review authority
- Director of Planning and Permitting
- Water surface rise limit
- 1 foot maximum, undetermined areas
- Required submittal
- Licensed engineer flood data
Summary
Any development in Honolulu's general floodplain zone A needs the director's review and approval before construction begins.
All proposed development within the general floodplain (unnumbered zone
A) shall be subject to review and approval of the director. The developer shall provide information signed and stamped by a licensed engineer, to evaluate the flooding and to determine the base flood elevation, and whether the project site is located within a floodway or flood fringe area, under § 21A-1.5(d).
(b) The director in reviewing the application may consult with other city, State, and federal agencies for their comments and recommendations, and shall review the related flood data such as flood elevation, riverine flood velocities, boundaries, etc., and evaluate and determine whether the proposed project is located within a floodway or flood fringe area.
(c) If it is determined that the proposed project is within a floodway area, the project shall comply with § 21A-1.7. If it is determined that the proposed project is within a flood fringe area, it shall comply with § 21A-1.8. Until a floodway or flood fringe area is designated, no development shall be allowed that would increase the water surface elevation of the base flood more than 1 foot at any point. (1990 Code, Ch. 21A, Art. 1, § 21A-1.10) (Added by Ord. 14-9)
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-10: Supplement 10, 12-2025 Ordinance No. 25-40 through Ordinance No. 25-56).
Full Breakdown
Under ROH § 21A-1.10, all proposed development within the general floodplain (unnumbered zone A) is subject to review and approval of the Director of Planning and Permitting. Developers must submit engineer-certified data showing the base flood elevation and whether the site sits in a floodway or flood fringe area. Until that determination is made, no development may raise the base flood water surface elevation more than 1 foot at any point.
Violations & Fines
Unapproved development in the floodplain violates ROH Chapter 21A and can be halted or require correction under the director's floodplain review authority.
Frequently Asked Questions
Who reviews floodplain development in Honolulu?
What must I submit for a flood zone project on Oahu?
Sources & Official References
Other rules in Honolulu County
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