If the county commission of any county determines to issue warrants under this chapter that are general obligations of such county, or if such county commission determines to issue warrants under this chapter that are limited obligations of such county payable solely from specified sources, then such county commission may assign and specifically pledge for the payment of the principal of and the interest on such general obligation warrants (as additional security for the payment thereof) or for the payment of the principal of and interest on such limited obligation warrants (as the sole source for the payment thereof), as the case may be, all or any portion of the funds derived from any one or more of the following sources that are not subject to previous pledges or covenants which would prevent the assignment and pledge hereby authorized, that are not required by the laws and Constitution of the State of Alabama to be devoted to other purposes, and that such county may at any time be authorized to levy, collect or receive:
(1) The proceeds from the general annual ad valorem tax which such county is authorized to levy without reference to the purpose thereof under the provisions of Section 215 of the Constitution of Alabama of 1901;
(2) The proceeds from the ad valorem tax which such county is authorized to levy under the provisions of Section 215 of the said Constitution for the purpose of paying any debt or liability created for the erection of necessary public buildings, bridges or roads;
(3) The proceeds from any other tax (including any ad valorem tax and any occupational, privilege, license or excise tax) that such county is authorized to levy at the time of the issuance of such warrants;
(4) Any payments in lieu of taxes made to such county by other governmental entities or by private persons or companies pursuant to contractual arrangements or laws in effect at the time of the issuance of such warrants;
(5) The portion of any tax levied and collected by any other governmental entity that shall be apportioned and paid to such county pursuant to laws in effect at the time of the issuance of such warrants;
(6) The income derived from the investment of moneys lawfully held by such county, including, without limitation thereto, the income derived from investments in which the proceeds of refunding obligations issued by such county may be invested until needed for the payment of the obligations to be refunded; and
(7) The revenues from any revenue producing properties owned, leased or operated by such county, including, without limitation thereto, any water system, sewer system, electric distribution system or other utility.
The pledge of any pledged funds for the payment of the principal of and interest on warrants issued by any county pursuant to this chapter, together with any covenants of such county relating to such pledge, shall have the force of contract between such county and the holders of such warrants. To the extent necessary and sufficient for making the payments secured by any pledge of pledged funds made pursuant to the provisions of this chapter, such pledged funds shall constitute a trust fund or funds which shall be impressed with a lien in favor of the holders of the warrants to the payment of which such pledged funds are pledged. In the event that more than one pledge should be made with respect to any pledged funds, then such pledges shall take precedence in the order in which they are made unless the proceedings making such pledge shall expressly provide that such pledge shall be on a parity with or subordinate to a subsequent pledge of such pledged funds. All warrants for which any pledge authorized by the provisions of this chapter may be made shall constitute preferred claims against that portion of the pledged funds so pledged, and shall have preference over any claims for any other purpose whatsoever.