La. Stat. tit. 38 § 1763
Gravity sub-drainage districts shall be composed of territory which is wholly within the limits and is less than the entire territory of a gravity drainage district. The sub-drainage district may be created from the land of one land owner. The governing body of any gravity sub-drainage district shall be the board of drainage commissioners of the gravity drainage district in which the sub-drainage district is situated. The resolution or resolutions creating gravity sub-drainage districts shall define the limits of the sub-drainage district, and the boundaries may be changed by the police jury or police juries creating the district, if the action be taken prior to the issuing of bonds or the levying of taxes therein. Gravity sub-drainage districts may also be formed on the petition of the board of commissioners of the gravity drainage district in which the proposed gravity sub-drainage district is situated, and they shall be formed upon a petition being presented as provided in R.S. 38:1751 for the compulsory creation of gravity drainage districts. The corporate seal of a gravity drainage district may be used as the corporate seal of any gravity sub-drainage district situated within its limits.
La. R.S. § 38:1763