The twenty-one members of the commission shall be residents of the areas to which their membership is apportioned, and the total membership shall be divided among the participating counties as follows:

1. Richland County: nine members

2. Lexington County: six members

3. Newberry County: three members

4. Fairfield County: three members

The membership from each county must be constituted as provided for in § 43-39-30.