96.170.  Terms of office of trustees — vacancies. — 1.  Unless the council has provided for a larger board of trustees, two of the trustees first appointed under the provisions of sections 96.150 to 96.228 shall hold office for terms of four years, and the remaining trustees first appointed shall hold office respectively for a term of one, two, and three years as indicated in the order of the mayor appointing them; thereafter each member shall be appointed for a term of four years.  When the council has provided for a larger board of trustees, the trustees first appointed shall hold office for terms so that as nearly as possible the terms of an equal number expire in each of the succeeding four years as indicated by the order of the mayor appointing them; thereafter each member shall be appointed for a term of four years.  If the council increases the size of the board by ordinance, the trustees then in office shall continue to serve for the remainder of the term for which appointed; the additional members shall be appointed such that as nearly as possible equal numbers expire in succeeding years.

  2.  Vacancies on the board shall be filled in the same manner provided herein for appointment of members.  Any person appointed to fill a vacancy on the board shall serve for the unexpired portion of the original term.

  3.  In the event the council has provided for a larger board of trustees and subsequently the size of the board is reduced, the trustees then in office shall continue to serve for the remainder of the terms for which they were appointed.  After the effective date of the reduction in size of the board, the mayor shall appoint as nearly as possible an equal number of trustees in each of the four succeeding years.