Sec. 9. The members of the commission shall be determined as follows:
(1) The legislative body of each county where any part of the joint district is located shall choose four (4) members.
(2) The legislative body of each municipality having a population of more than three thousand (3,000) and less than fifteen thousand (15,000), that passes an ordinance establishing a joint district and that is located within five (5) miles of the joint district shall choose three (3) members.
(3) The city plan commission (or similar body) of each municipality having a population of more than twenty-five thousand (25,000) and less than fifty thousand (50,000), that passes an ordinance establishing a joint district and that is located within ten (10) miles of the joint district shall choose two (2) members.
(4) The executive of each municipality meeting the population, proximity, and ordinance requirements of subdivision (3) shall choose one (1) member.