(a) All revenues in excess of all obligations of the association of every nature which are not otherwise pledged or restricted as to disposition and use by the terms of any trust indenture entered into by the association for the security of bonds issued under this part, together with all receipts and gifts of every kind and nature whatsoever, shall be and become the association fund.

(b) The association, in its discretion, shall pledge or utilize the association fund for any one or more of the following purposes:

(1) Pledges to the payment of any bond issue requirements, or to sinking or reserve funds, as may be provided for under the terms of this part;

(2) Payment of any outstanding unpaid bond obligations or administrative expenses;

(3) The most advantageous obtainable purchase, redemption, and retirement of the association's bonds pursuant to privileges accorded to the association in the various issues of bonds outstanding;

(4) Investment or reinvestment in any of the following obligations:

(A) Obligations of this state or other states;

(B) Obligations issued by the United States;

(C) Obligations fully insured or guaranteed by a United States government agency;

(D) Obligations of any corporation of the United States;

(E) Prime bankers' acceptances;

(F) The local government investment pool established by Chapter 83 of Title 36, the "Local Government Investment Pool Act";

(G) Repurchase agreements;

(H) Obligations of other political subdivisions of this state; and

(I) Certificates of deposit;

provided, however, that funds so invested and income from such investments shall always be available to and ultimately expended for other purposes authorized by this chapter.

(c) After all outstanding bonds or obligations of the association issued to pay the cost of the project or any part thereof have been paid or satisfied by payment redemption and retirement, or otherwise, all revenues from the project in excess of those necessary to maintain, operate, and manage such project (including extensions, renewals, and additions thereto), unless otherwise allocated or pledged as provided in this Code section, shall be paid to the state treasury and become a part of the general funds of the state.