Mo. Rev. Stat. § 204.331
The county commission, or county legislature, may, in addition to all powers herein granted or implied, create a subdistrict or subdistricts within the county, which subdistrict, when created, shall be a body corporate and politic. Creation of the subdistrict or subdistricts shall be in the manner hereinafter provided, but in all other respects the administration and operation of the subdistricts shall be in the manner provided by sections 249.430 to 249.660. Either the county commission or the members of the county legislature elected from all or a portion of the subdistrict shall act as the governing body of the sewer subdistrict. Each subdistrict so created shall, in addition to the powers granted by sections 249.430 to 249.660, have the power and ability to contract with the common sewer district created pursuant to sections 204.250 to 204.470, or with other subdistricts for the collection, transportation and treatment of sewage or any function associated therewith, including but not limited to engineering, construction, maintenance, repair, and administrative services required for the collection, transportation, and treatment of sewage.
§ 204.331, RSMo