Ala. Code § 11-99A-48: Additional Security for Bonds.

(a) A board may pledge out of bond proceeds or other sources reserve funds for the repayment of bonds. In addition, the district, any other public person, or any other person may mortgage, subject to foreclosure, for the benefit of bonds, any improvements constructed, acquired, or installed with proceeds of the bonds.

(b) A board, the appointing government, any other public person, or any other person may pledge to the payment of bonds all or part of a grant, donation, revenue, or income received or to be received from the government of the United States or any other public or private source, whether or not it is received pursuant to an agreement or otherwise.