La. Stat. tit. 33 § 4076
The board may employ all necessary clerks, engineers, firemen, and other skilled and unskilled employees necessary and proper to the efficient administration, operation and control of the public sewerage, water, and drainage systems. All the employees, except unskilled laborers, shall be appointed only after they have passed the civil service examination administered by the civil service commissioners of the city of New Orleans. Other than executive management positions, if an employment position cannot be filled with a New Orleans resident within ninety days after the position has been advertised, the board may employ a person who is not a New Orleans resident and who shall remain exempt from the city's residency requirement for the duration of his employment. They shall hold their positions during good behavior and shall be removed only for cause. Nothing herein shall be construed as preventing the board from dispensing with the services of unnecessary employees.
Civil service rules shall not apply to the executive director, the general superintendent, or the Board of Advisory Engineers.
La. R.S. § 33:4076