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

Kauai County's floodplain ordinance is codified at Chapter 15, Article 1 of the Kauai County Code, originally adopted as Ordinance No. 831 on September 9, 2005 and most recently amended by Ordinance No. 1091 effective February 10, 2021. The Department of Public Works Engineering Division administers the program, reviewing proposed development for compliance with the ordinance and NFIP regulations. The current effective Flood Insurance Rate Map and two-volume Flood Insurance Study for Kauai County took effect February 26, 2021, replacing the previous November 26, 2010 mapping based on updated coastal storm surge and riverine modeling. FEMA flood zones used in Kauai County include Zone A (general floodplain without base flood elevations), Zone AE (with established BFEs), Zone AO (shallow flooding), Zone AEF (regulatory floodway), Zone X (areas of minimal flood hazard), Zone D (areas of undetermined hazard), and the coastal high hazard Zones V and VE which align with tsunami inundation zones along Kauai's shoreline. A Flood Development Permit issued by the DPW Engineering Division is required before any new construction, substantial improvement, fill, grading, or substantial structural alteration in a mapped Special Flood Hazard Area. Kauai County mandates that V-zone construction be certified by a Hawaii-licensed civil or structural engineer or architect, with structures elevated on pile or column foundations open below the base flood elevation. The NFIP substantial improvement and substantial damage rule applies, where any repair or improvement equal to or exceeding 50 percent of the structure's pre-improvement market value triggers full Chapter 15 compliance for the entire building. Following the April 14-15, 2018 north shore disaster in which the Waipa Foundation rain gauge near Hanalei recorded 49.69 inches of rainfall in 24 hours, the highest 24-hour rainfall total ever measured in the United States, and severe flash flooding and landslides damaged or destroyed over 532 homes and isolated Wainiha and Haena for months, the County intensified floodplain enforcement and pursued post-disaster mitigation funding through the Disaster Recovery and Mitigation Program in the Housing Agency. On October 14, 2022, Mayor Derek Kawakami signed Bill 2879, codified as Ordinance 1118, amending Chapter 8 (Comprehensive Zoning Ordinance) Article 12 to establish the Sea Level Rise Constraint District (SLR-XA), making Kauai the first known county in the United States to regulate construction based on scientific projections of future sea level rise. Drafted in partnership with the University of Hawaii Manoa Climate Resilience Collaborative, the ordinance is built on the 2017 Hawaii Sea Level Rise Vulnerability and Adaptation Report's projection of 3.2 feet of sea level rise this century, requiring new residential construction and substantial improvements within the SLR-XA to elevate the lowest floor including basements at least 2 feet above the highest projected sea level rise flood elevation, and nonresidential structures at least 1 foot above. The Kauai Sea Level Rise Constraint District Viewer maps the district based on annual high wave run-up and passive flooding hazards. The ordinance won the American Planning Association's 2023 National Resilience and Sustainability Award. Coastal parcels are also subject to Hawaii Revised Statutes Chapter 205A Coastal Zone Management Act, with Special Management Area permits and shoreline setback determinations administered by the Kauai Planning Commission under Ordinance 979 (adopted December 5, 2014, amended by Ordinance 1088 effective February 4, 2021), which establishes a shoreline setback line of 40 feet plus 70 times the annual coastal erosion rate from the certified shoreline, plus a mandatory 20-foot additional safety buffer for episodic coastal events and sea level rise. Kauai County also operates under the Hanalei Estuary Management Plan, special management area rules promulgated under HRS Chapter 205A. Tsunami evacuation zones are mapped in two tiers by the Hawaii Emergency Management Agency and Kauai Emergency Management Agency, with Tier 1 standard tsunami evacuation maps based on historical tsunamis and Tier 2 Extreme maps showing worst-case scenarios.