If more than one series of bonds are issued payable from the revenues of any utility, priority of the mortgage of such utility and pledge of the revenues thereof shall depend on the time of the delivery of the bonds, each series rights priming series of bonds subsequently delivered. However, as to any issue or series of bonds which may be authorized as a unit but delivered from time to time in blocks, the governing body may in the proceedings authorizing the issuance of the bonds provide that all of the bonds of such series or issue shall run concurrently regardless of the time of delivery.
La. R.S. § 45:1141