Ala. Code § 11-57-22
Any portion of the principal proceeds derived from the sale of the bonds which the board may determine is not presently needed for any of the purposes for which the bonds are authorized to be issued and any other moneys of the authority which the board may determine will not be presently needed by the authority may, on order of the board, be invested in any securities that are direct obligations of the United States of America or the principal of and interest on which are unconditionally and irrevocably guaranteed by the United States of America. Any securities in which any such investment is made may, at any time and from time to time on order of the board, be sold or otherwise converted into cash. The income derived from any such investments shall be disbursed on order of the board for any purpose for which the authority may lawfully expend funds.
Ala. Code § 11-57-22 (1975)