Mo. Rev. Stat. § 91.260
The waterworks system, when acquired by purchase or erected by the city, shall be under the management and control of a board known as "The Board of Waterworks Commissioners", which shall be composed of three residents of the city, well known for their intelligence and integrity, who shall be appointed by the mayor with the approval of the city council. As soon as convenient after the members of the board have been chosen, the board shall hold a meeting at the city council room of such city, and organize by the election of a president, and adopt a corporate seal, and at such first meeting they shall determine by lot the term of office of each member, so that one shall serve for one year, one for two years and one for three years, and whenever the term of office of a member of the board expires, the mayor of the city, with the approval of the city council, shall appoint a successor to serve a full term of three years; and in case any other vacancy arises in the board, it shall be filled in like manner for the unexpired term. Each of the commissioners shall give bond in the penal sum of five thousand dollars, with two solvent securities, for the faithful performance of their duties, such bond to be approved by the mayor. Any member of such board shall be suspended or removed in the same manner and for like cause as an appointive city officer. The board shall keep a record of its proceedings, and the city clerk of the city, by virtue of his office, shall be secretary of the board of waterworks commissioners, and shall be the custodian of the seal, and shall serve without further compensation than that received as city clerk. Each member of the board may, by ordinance of the council of the city, be paid out of the revenues derived from the operation of the plant, a salary not exceeding the sum of five hundred dollars per year. No person holding an office under the city government, either elective or appointive, shall be eligible to appointment on the board of waterworks commissioners, and no more than two of such commissioners shall belong to the same political party.
§ 91.260, RSMo