9 rules for unincorporated Hawaii County, Hawaii.
Verified from official government sources
Hawai'i County has no fixed grass-height number. Overgrown lots are handled as public nuisances: under HRS 46-1.5(12) the county may compel clearing of uncultivated undergrowth from unoccupied lots and bill or lien the owner if they ignore notice.
HRS 46-1.5(12)
Each county shall have the power to enact and enforce ordinances necessary to prevent or summarily remove public nuisances and to compel the clearing or removal of any public nuisance, refuse, and uncultivated undergrowth from streets, sidewalks, public places, and unoccupied lots.
You may trim your own trees. For trees and vegetation along county roads, Public Works' Highway Maintenance Division handles roadside trimming and clearance. Designated exceptional trees need county review before any trimming that could destroy them.
You can generally remove ordinary trees on your own Big Island property without a county permit. The exception is a tree the county has designated 'exceptional' under HRS Chapter 58, which requires county review before removal.
The County of Hawai'i can compel clearing of weeds and 'uncultivated undergrowth' from unoccupied lots as a public nuisance under HRS 46-1.5(12). After notice, the county may clear the lot and lien the owner for the cost.
HRS 46-1.5(12)
...to compel the clearing or removal of any public nuisance, refuse, and uncultivated undergrowth from streets, sidewalks, public places, and unoccupied lots.
The County of Hawai'i Department of Water Supply can restrict water use during shortages, drought, or equipment problems, often ordering 25% cuts (50% for irrigation). Its Rules let it 'restrict the use of water by any reasonable method of control.'
DWS Rules & Regulations, Section 3-2(2)
Whenever, in the Department's opinion, special conservation measures are advisable in order to forestall water shortage and a consequent emergency, the Department may restrict the use of water by any reasonable method of control.
Rainwater catchment is legal and common on the Big Island — many Puna and off-grid homes rely on it. The County Department of Water Supply does not recognize or regulate catchment, and no county permit is required for a private system.
Hawai'i County DWS, Rainwater Catchment page
the Department of Water Supply (DWS) does not recognize nor regulate Rainwater Catchment
There is no county rule requiring native landscaping, but the Big Island is ground-zero for invasive-species control. Planting or spreading state-listed noxious/invasive pests (coquí frog, miconia, little fire ant, albizia) is regulated by the state, not the county.
The County of Hawai'i has no ordinance banning or specifically regulating artificial turf on residential yards. Installation must still meet zoning setbacks, lot-coverage limits, and any drainage/grading permit requirements under the Hawai'i County Code.
Home composting is allowed and encouraged in Hawai'i County. The county runs green-waste diversion at its transfer stations and recycling programs, but there is no permit for a backyard compost bin — just keep it from becoming a nuisance or rodent/pest attractant.
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