La. Stat. tit. 33 § 140.165
The regulations, restrictions, and boundaries may, from time to time, be amended, supplemented, changed, modified, or repealed. However, in case of a protest against a change duly signed and acknowledged by the owners of twenty percent or more either of the areas of land exclusive of streets and alleys included in the proposed change or within an area determined by lines drawn parallel to and two hundred feet distant from the boundaries of the district proposed to be changed, the amendment shall not become effective unless at least three-fifths of all the members of the governing authority of the parish shall vote in favor thereof. The provisions of R.S. 33:140.164 relating to public hearing and official notice shall apply equally to all changes or amendments.
La. R.S. § 33:140.165