Hawaii County, HI Environmental Rules: Flood Zones (2026)

Hawaii County's floodplain ordinance is Chapter 27 of the Hawaii County Code, titled Floodplain Management, and administered by the Director of the Department of Public Works through the Engineering Division. The Flood Insurance Rate Maps and Flood Insurance Study published by FEMA are adopted by reference and identify Special Flood Hazard Areas across the island. Flood zones used in Hawaii County include Zone A (general 100-year floodplain without detailed BFEs), Zone AE (100-year floodplain with established Base Flood Elevations), Zones AH and AO (shallow flooding and sheet flow), Zone AEF (regulatory floodway), Zone VE (coastal high-hazard with wave velocity), and Zone X (moderate or minimal flood hazard, including 500-year floodplain). Under Chapter 27 a Flood Development Permit issued by the DPW Engineering Division is required prior to any development - including new construction, substantial improvement, fill, grading, or substantial structural alteration - within a mapped Special Flood Hazard Area. Hawaii County imposes a higher regulatory standard than federal NFIP minimums by requiring 1 foot of freeboard, meaning the lowest floor (including basement) of new and substantially improved structures must be elevated at least one foot above the Base Flood Elevation, and building permit plans must show both the BFE and the one-foot-above-BFE elevation. Coastal high-hazard VE zone development requires elevation on pile or column foundations open below the BFE and engineer or architect certification. The NFIP substantial improvement and substantial damage rule applies, so any reconstruction, addition, or improvement equal to or exceeding 50 percent of the structure's pre-improvement market value triggers full Chapter 27 compliance for the entire building, and Hawaii County applies cumulative substantial improvement provisions. Hawaii County participates in FEMA's Community Rating System, which provides automatic flood insurance premium discounts on NFIP policies in Special Flood Hazard Areas across the county's roughly 4,400 active NFIP policies; as of April 2023 Hawaii became the first state with 100 percent CRS participation. Beyond FEMA flood zones, the Big Island faces two additional hazards that other Hawaiian counties largely do not. First, the USGS Hawaiian Volcano Observatory maintains a Lava Flow Hazard Zone map (originally 1974, last revised 1992) that divides the island into 9 zones based on the location and frequency of historic and prehistoric eruptions: Zones 1 and 2 (Kilauea and Mauna Loa rift zones) are highest hazard and largely uninsurable for lava under standard homeowner policies; Zone 3 includes most of Puna and parts of Ka'u and South Kona; Zone 4 covers all of Hualalai; Zones 5 and 6 are areas on Kilauea and Mauna Loa currently protected by topography; Zone 7 is the younger flank of Mauna Kea; Zone 8 is the rest of Mauna Kea; and Zone 9 is Kohala Volcano, which last erupted over 60,000 years ago. Second, the Hawaii Emergency Management Agency (HIEMA) and Hawaii County Civil Defense publish tsunami evacuation zone maps, with a base Tsunami Evacuation Zone (yellow on official maps) and an Extreme Tsunami Evacuation Zone (purple) for locally generated near-shore tsunamis - both are particularly significant on the Big Island given its position at the southern end of the Hawaiian chain and the 1946 and 1960 tsunamis that devastated downtown Hilo. Coastal parcels are also subject to Hawaii Revised Statutes Chapter 205A Coastal Zone Management Act and Special Management Area (SMA) permit review by the Hawaii County Planning Department for any development within the SMA boundary along the shoreline. Property owners can obtain a flood zone determination using the FEMA Flood Map Service Center, the State of Hawaii Flood Hazard Assessment Tool at fhat.hawaii.gov, or by contacting the Hawaii County Floodplain Manager.