Whenever a public agency enters into a contract as authorized by Sections 17-17-301 through 17-17-349, and the payments are to be made either wholly or partly from the revenues of the authority's facilities, the duty is hereby imposed on the public agency at the direction of the authority to fix, establish and maintain, and from time to time adjust, the rates or fees charged by the public agency for the service of such facilities to the end that the revenues from such facilities, together with any ad valorem taxes levied for such payments, will be sufficient at all times to pay: (a) the expense of operating and maintaining such facilities; (b) all of the public agency's obligations to the authority under such contract; and (c) all of the obligations under and in connection with any outstanding bonds issued to finance in whole or in part such facilities.