Hawaii County, HI Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing chapter
- HCC Ch. 27, Floodplain Management
- Facility change approval
- Required before altering any drainage facility
- Design manual incorporated
- DPW Storm Drainage Standard, Oct. 1970 ed.
- Civil fine range
- $500-$1,000 per day, continuing violation
- Criminal penalty
- Misdemeanor, up to $1,000 fine or 1 year
- Enforcing agency
- Department of Public Works, Hawai'i County
Summary
Hawaii County regulates drainage facilities under HCC Chapter 27, Floodplain Management. Any new construction or substantial improvement next to a drainage facility, even outside mapped flood hazard zones, needs Department of Public Works review, and nobody may modify, line, or alter a drainage facility without director approval.
Section 27-25. Standards for improvements adjacent to drainage facilities. New construction, improvements to repetitive loss structures, and substantial improvements proposed adjacent to drainage facilities outside of the special flood hazard areas identified on the Flood Insurance Rate Maps shall be subject to review and approval of the director of public works. (a) Upon request by the director of public works, further information concerning base flood elevation, floodways, surface water runoff, existing and proposed drainage patterns, and other information, including a detailed flood elevation study, drainage report, and findings and opinions by a licensed professional civil engineer, shall be provided to evaluate potential flooding. (c) A drainage facility shall not be modified, constructed, lined, or altered in any way to accommodate the improvement without the approval of the director of public works.
Full Breakdown
" The director can demand a base flood elevation study, floodway data, surface water runoff analysis, drainage patterns, and a report signed by a licensed professional civil engineer before signing off. Critically, subsection (c) bars anyone from modifying, constructing, lining, or altering a drainage facility to accommodate an improvement without that approval. Section 27-26 folds the Department of Public Works' "Storm Drainage Standard," October 1970 edition or latest revision, directly into the chapter, so every subdivision engineer and consultant designing drainage facilities or preparing flood hazard studies on the Big Island must build to that manual.
Applicability under § 27-5 extends the chapter to floodway fringe zones AE/AH/AO, the floodway itself, coastal high-hazard (tsunami) zones V/VE, the general floodplain (Zone A), and "land adjacent to drainage facilities," not just properties inside a mapped flood zone. County inspectors carry a right of entry under § 27-32 to check compliance on both public and private land, and § 27-37 lets Public Works order removal of any encroachment or obstruction placed under, over, or through a drainageway, floodway, levee, or watercourse.
Violations & Fines
Under § 27-33, Public Works serves a written notice of violation by certified mail or hand delivery identifying the section violated, the tax key number, and a compliance deadline. If noncompliance continues, § 27-34 authorizes a civil fine of $500 to $1,000, escalating to $500 to $1,000 per day for a continuing violation, with a hearing right under HRS Chapter 91 before any fine is imposed. Section 27-36 makes any violation of the chapter a misdemeanor punishable by a $1,000 fine or up to one year in jail, and treats each day a violation continues as a separate offense; the County can also seek injunctive relief in circuit or federal district court under § 27-35.
Frequently Asked Questions
Do I need county approval to alter a drainage ditch on my Big Island property?
Does this apply if my lot is not in a FEMA flood zone?
What design standard governs subdivision storm drainage on Hawaii Island?
What happens if I ignore a drainage violation notice?
Sources & Official References
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