When Hawai‘i County passed Bill 123 (now Ordinance 24-70) in late 2024, many celebrated. It looked like homeowners could finally build Accessory Dwelling Units (ADUs)—small, secondary homes—on almost any residential or agricultural property.
And yes, the bill specifically says:
“Accessory dwelling units shall be permitted on a building site within the RS, RD, RA, FA, and A districts.”
That sounds clear enough, right?
But here’s the important catch that many people miss:
“Any building site within the State land use agricultural district shall be subject to agricultural requirements for farm dwellings as established by ordinance or by rule of the director…”
Translation: State Law Overrides County Law.
⚠️ County Zoning Isn’t the Whole Story
For Bill 123 to apply to your agricultural-zoned property, your land must be:
- Zoned Agricultural (Ag) by Hawai‘i County AND
- Located in the State Urban District.
But here's the problem: almost all agricultural parcels on the Big Island are actually within the State Agricultural District—not Urban. Under Hawai‘i State law (specifically HRS § 205-4.5), properties within the Agricultural District must have farm dwellings used directly in support of agriculture. Short-term vacation rentals and general residential uses are prohibited.
This means the flexibility promised by Bill 123 doesn’t apply to the vast majority of Big Island properties labeled “Ag.”
🧾 When Might You Actually Build an ADU on Ag Land?
Realistically, you could potentially build an ADU only if:
- Your Ag-zoned property is in the State Urban District (rare, mostly near town centers).
- The ADU qualifies clearly as a farm dwelling supporting agricultural operations.
- You fall under a special exemption (such as pre-1976 subdivisions).
Otherwise, the restrictions from State law will trump your County permissions.
🚿 A Quick Note on Water and Infrastructure
Even if zoning aligns, practical restrictions might still limit your options. For instance, each dwelling typically requires separate water connections or catchment systems. Confirming infrastructure capability is essential before investing in any ADU project.
✅ Actionable Steps for Property Owners
Before you start building plans or spending money:
- Verify your State Land Use Classification: Use the official State Land Use Map.
- Contact Hawai‘i County Planning Department: Get written verification of your property's zoning and permitted uses.
- Consider consulting a local land-use professional for a clear and accurate property assessment.
🏁 The Bottom Line
Bill 123 was a well-intentioned attempt to increase affordable housing—but when it comes to agricultural land, it simply isn’t practical for most Big Island property owners. The critical factor isn't just County zoning, it's your State Land Use designation.
If you're unsure about your property or need clarity navigating these laws, feel free to contact me. As a Realtor committed to accurate guidance, my goal is to ensure you know exactly what's possible—and what's not.
— Dan Tousignant, REALTOR® serving East Hawai‘i
