Mo. Rev. Stat. § 248.180
When the object for which a sanitary district was organized is accomplished by the completion of the main channel, drains or sewers, contemplated and adopted in the general plan, and when the areas of divided jurisdiction are drained or otherwise provided for (which facts the circuit court for the district in which the whole or the major part of the territory embraced in the district shall determine), then the board of trustees of such sanitary district shall cease to exist at the expiration of sixty days after the date of the decree of court expressing such determination. But provision shall be made for the fulfillment of all contracts and obligations which have been made by said board of trustees, the responsibility therefor being assumed by the city or county directly interested. Provision shall also be made for the prompt payment of all outstanding bonds of the sanitary district.
§ 248.180, RSMo