La. Stat. tit. 45 § 1140
When any sale of the mortgaged property shall be held under the provisions of R.S. 45:1137 through 45:1141, the purchaser at the sale, and his successor or assign, shall be vested with an exclusive permit and franchise to maintain and operate the property purchased, and to continue to supply to the public the commodities, products or services previously supplied by the utility, with the same powers and privileges previously enjoyed by the political subdivision in the operation of said utility. This franchise shall continue for such period not exceeding forty years from the date of sale as may be fixed by the governing body in the resolution authorizing the bonds, and shall be subject to all statutory limitations pertaining to the granting of municipal franchises.
La. R.S. § 45:1140