Section 11. The department shall assess the Massachusetts Water Resources Authority for the fiscal year costs of operating the division and other authorized charges relating to the watershed system formerly under the care, custody and control of the division of watershed management of the metropolitan district commission, including 100 per cent of the amounts to be paid in that fiscal year in trust by the authority to the division for application to payments in lieu of taxes pursuant to chapter 59, less any and all revenues generated by the division which shall include, but not be limited to, the sale of hydroelectricity, recreational or permit fees, revenues from the sale of wood products harvested on department watershed lands, and any access fees established pursuant to chapter 436 of the acts of 1990. The assessment shall be established annually by the commissioner of the department. The commissioner of the department shall certify to the executive director of the authority on or before September 15, the current fiscal year obligations due by the authority for the operations of said division relating to the watershed system formerly under the care, custody and control of the division of watershed management of the metropolitan district commission. The commissioner shall bill the treasurer of the authority on October 1, January 1, April 1 and June 30 of each fiscal year for said fiscal year's obligations. Within 30 days of receipt of the department bill, the treasurer of the authority shall remit the total billed amount to the commission. Revenues received from the June 30 billing shall be credited to that fiscal year. The commissioner of the department shall forward to the treasurer of the commonwealth the revenues generated by the division which shall be credited to the General Fund.