Haw. Rev. Stat. § 46-49: Interest on deposits.

If any money deposited by the director of finance, under the provisions of section 46-48, belongs to the waterworks funds, then any interest received on the same shall be paid into and credited to the funds, and if any money so deposited belongs to a bond fund, then any interest received on the same shall be paid into and credited to the fund which provides for the payment of interest on bonds.