When all bonds and notes issued under the provisions of this article to finance the state water and power plan and the interest thereon shall have been paid or a sufficient amount for the payment of all such bonds and notes and the interest thereon to the maturity thereof shall have been set aside in trust for the benefit of the holders of such bonds and notes, all projects then included in the state water and power plan shall thereafter be operated and maintained by the director and the authority, and water and power rates shall be reduced accordingly unless the legislature shall provide that the revenues therefrom shall be deposited in the general fund of the state, in the state water and power development fund or as the legislature may otherwise direct.