La. Stat. tit. 33 § 130.18
When an industrial area shall be created including territory which is a part of a preexisting special service district which furnishes any of the services enumerated in R.S. 51:1202, such territory shall continue to be subject to taxes of the special service district which had previously been levied. No new tax levied by any such special service district shall apply to any territory within an industrial area unless such tax is a renewal or extension of a previously existing tax, the proceeds of which are to be used to continue an existing service. No increase of an existing tax levied by any such special service district shall apply to any territory within an industrial area unless, because of increased maintenance or other costs, such increase is necessary to continue to provide an existing service.
La. R.S. § 33:130.18