The commission shall, once in each six months, make out and verify under oath, and file with the board, a detailed statement of its proceedings, showing:
(a) The amount of money in the harbor fund at the time of the last report.
(b) The amounts of all donations since received and the purpose for which the donations were made.
(c) The amount since expended, and the purpose for which it was expended.
(d) The balance remaining on hand in the fund.