The Washington state ferry system shall be efficiently managed, operated, and maintained as a revenue-producing undertaking. Subject to the provisions of *RCW
47.60.326 the commission shall maintain and revise from time to time as necessary a schedule of tolls and charges on said ferry system with other moneys deposited in the Puget Sound ferry operations account for maintenance and operation and all moneys in the Puget Sound capital construction account available for debt service will produce net revenue available for debt service, in each fiscal year, in an amount at least equal to minimum annual debt service requirements as hereinafter provided. Minimum annual debt service requirements as used in this section shall include required payments of principal and interest, sinking fund requirements, and payments into reserves on all outstanding revenue bonds authorized by RCW
47.60.400 through **
47.60.470.
The provisions of law relating to the revision of tolls and charges to meet minimum annual debt service requirements from net revenues as required by this section shall be binding upon the commission but shall not be deemed to constitute a contract to that effect for the benefit of the holders of such bonds.