Funds deposited in the trust fund and all earnings from the investment of these funds, after allowances for operating expenses, are available for disbursement upon authorization of the department. However, in any year in which more than two hundred thousand dollars is deposited in the trust fund, twenty-five percent of the amount over two hundred thousand dollars and earnings from the investment of these funds must be placed in a separate account. When the assets of this separate account exceed five million dollars, no further deposits are required to be made to the separate account and all future earnings from the investment of the monies in this separate account also are available for distribution upon authorization of the department.