Mo. Rev. Stat. § 242.230
The chief engineer shall make a report in writing to the board of supervisors once every twelve months and more often if said board shall so require. Upon receipt of the final report of said engineer concerning surveys made of the lands and other property contained in the district organized, and plans for reclaiming the same, the board of supervisors shall adopt such report or any modification thereof approved by the chief engineer after consulting with the chief engineer or someone representing the chief engineer, and thereafter such adopted report shall be the plan for draining, leveeing or reclaiming such lands and other property from overflow or damage by water, and it shall after such adoption be known and designated as "the plan for reclamation", which plan shall be filed with the secretary of the board of supervisors and copied by the secretary into the records of the district. Supplemental plans for draining, leveeing, or reclaiming some or all of the lands and other property in the district from overflow or damage by water may be adopted by the board of supervisors from time to time as deemed necessary by the board of supervisors. The aforesaid supplemental plans may supplement, alter or modify the plan for reclamation and shall become a part thereof.
§ 242.230, RSMo