A county with a population of 300,000 or less shall appoint one member of the bay district board; a county with a population of 750,000 or less, but more than 300,000, shall appoint two members of the bay district board; a county with a population of 1,000,000 or less, but more than 750,000, shall appoint three members of the bay district board; and a county with a population of more than 1,000,000 shall appoint four members of the bay district board.