Honolulu Tree and Parking Lot Requirements for Stormwater

To support stormwater management and reduce heat from paved surfaces, Honolulu requires large parking lots (10+ spaces) to include shade trees. For every 6 spaces, one 2-inch caliper tree is required (or one 6-inch caliper tree per 12 spaces). Trees must be planted in areas at least 9 square feet (3 feet wide minimum), spaced to evenly distribute shade. As an alternative, tree boxes designed to treat stormwater runoff may be used, provided they meet city stormwater quality standards.