La. Stat. tit. 33 § 3881.1
Notwithstanding any other provision of law to the contrary, where any sewerage treatment plant as defined by R.S. 40:1281.1 is established outside of an incorporated municipality and outside of any active sewer district, the site for the facility as well as the facility itself may be under the authority, control, and supervision of the applicable parish governing authority for its operation, management, and maintenance, subject to the approval of the office of health and environmental quality. It shall be the duty of such parish governing authority to effectuate the purposes of this Section, and to that end each such governing authority shall adopt such ordinances as may be necessary and appropriate thereto.
The provisions of this Section shall not apply to any municipally owned sewerage treatment plant which may be located outside the corporate limits or to any industrial plant which provides its own sewerage treatment.
La. R.S. § 33:3881.1