La. Stat. tit. 45 § 1203
The public service commission shall have and exercise all necessary power and authority to supervise, govern, regulate and control all privately owned and operated sewerage disposal companies and works not under the supervision and control of any city, town or parish as provided by Section 7 of Article VI of the Constitution, and to fix reasonable and just charges for the services furnished by such sewerage disposal companies and works.
The said commission shall have power to adopt and enforce such reasonable rules, regulations and modes of procedure as it may deem proper for the discharge of its duties in connection with such companies and works, and it may summon and compel the attendance of witnesses, swear witnesses, compel the production of books and papers, take testimony under commission and punish for contempt as fully as is provided by law for the district courts.
La. R.S. § 45:1203