La. Stat. tit. 38 § 1660
Any two or more adjacent drainage districts organized or reorganized under the provisions of this Part, whether in the same or different parishes, may be united and consolidated into one drainage district and the new district and the board of commissioners thereof shall have all of the rights, powers, privileges, and duties of any other drainage district created and organized under this Part.
In order to effect the consolidation, the land owners owning a majority of the acreage in each of the drainage districts shall present a joint petition to that effect approved by the board of commissioners and the chief engineers of the drainage districts to the police jury of the parish in which the districts are situated, or if they are situated in more than one parish, then to the policy jury of the parish in which the majority of land in the proposed consolidated district is situated. The petition shall also contain a statement showing the names and boundaries of the original districts, the name and boundaries of the proposed consolidated district, and shall be accompanied by a certificate as to land owners and acreage as provided in R.S. 38:1604, and the approval of the board of state engineers as provided in R.S. 38:1605.
The police jury shall adopt an ordinance creating the consolidated drainage district and appointing commissioners therefor in the same manner as provided in this Part for creating original drainage districts. The ordinance shall be recorded by the clerk of court and recorder of each parish in which is situated any land in the consolidated drainage district in the drainage district record of his office.
The consolidated drainage district shall then be subject in all respects to the provisions of this Part, and all of the lands and property in the new district shall be subject to the same liens, liabilities, and obligations that may have existed against the lands and property in the original districts composing the new district.
La. R.S. § 38:1660