The Huron-Clinton metropolitan authority shall be directed and governed by a board of commissioners, 1 to be elected from each county of the metropolitan district by the boards of supervisors of the respective counties, and 2 to be appointed by the governor of Michigan. The elected commissioners shall be electors of their respective counties, and the appointed commissioners shall be electors of the metropolitan district. The appointed commissioners shall serve for 4 year terms or until their successors are appointed, except that for the first board 1 shall be appointed for a 2 year term. The terms of the elected commissioners shall be staggered so that not more than 1 term shall expire in any 1 year, and after the first board no terms shall be less than 6 years. For the first board the terms of the elected commissioners shall be in the order of the populations of the several counties, the commissioner from the most populous county having the longest term.