Haw. Rev. Stat. § 49-18
The director of finance may invest any money held as reserves or in sinking funds or not required for immediate disbursement, including proceeds of the revenue bonds, which in the director's judgment are in excess of the amounts necessary for the meeting of immediate requirements, in securities permitted by the resolution or resolutions and which constitute legal investments for public funds. Income derived therefrom shall be treated as revenue of the undertaking or loan program; expenses of purchase, safekeeping, sale, and redemption, and all other expenses of the undertaking or loan program. Securities so purchased shall be considered as being deposited in the custody or control of the director of finance and shall be legally secured as required by law.
HRS § 49-18