The board of directors of any irrigation district in this state which is furnishing or may furnish irrigation water, domestic water, electric power, drainage or sewerage services for which rates or tolls and charges are imposed or contract payments made, or any combination of such services, shall have authority to issue and sell bonds of the district payable from revenues derived from district rates or tolls and charges or contract payments for such service or services, and to pledge such revenues from one or more of such services for the payment and retirement of bonds issued for irrigation water, domestic water, electric power, and drainage or sewer improvements: PROVIDED, That nothing in this section shall authorize a district which is not on March 8, 1973, engaged in providing electrical service permission to pledge revenue from water and sewer service to support the issuance of revenue bonds for the acquisition or construction of electrical power facilities other than those authorized by *RCW
87.03.015(1), as now or hereafter amended.