Mo. Rev. Stat. § 249.451
A county commission serving as the governing body of any sewer district, now or hereafter existing and created in accordance with subsection 1 of section 249.450, may by resolution delegate and assign responsibility for the control and operation of such district to the board of trustees of any common sewer district formed under sections 204.250 to 204.470 which lies wholly or partially within the same county, subject to the acceptance of such delegation and assignment by such board of trustees. Upon such acceptance, the delegation and assignment shall become irrevocable except by action of both the county commission and the board of trustees of the common sewer district, and the board of trustees of the common sewer district shall have the same powers and duties with regard to the sewer district created under subsection 1 of section 249.450, as are provided the county commission under chapter 249.
§ 249.451, RSMo