La. Stat. tit. 33 § 4089
The board may not obligate itself or create any debt for construction purposes in excess of the cash amount of the proceeds of any sewerage, water and drainage serial bonds, the public improvement fund, the construction and extension fund of the sewerage and water board, the surplus from the water revenues, and any surplus from taxes or other sources. All debts and obligations in excess of the actual cash amount of those funds shall be absolutely null and void; nor may the board, in any year, expend any sum of money, or create any debt for the maintenance and operation of the public systems of sewerage, water and drainage, in excess of the actual revenues of that year. All debts and obligations in excess of the actual revenues of that year, shall be absolutely null and void. The surplus revenue of one year may be carried forward and added to the revenues of the following year; but no contract or expenditures of any kind shall ever be made in anticipation of any surplus of either construction or maintenance fund.
La. R.S. § 33:4089