Every drainage district consisting of 5,000 acres or more, and every city, shall constitute a separate road district. The county court shall not divide such territory to include any of it in any other road district unless the people of the drainage district or city, by majority vote at an election held pursuant to law, vote that the territory be included by the county court in a road district established by the county court. The county court may include in the road district of any drainage district contiguous property adjoining or adjacent to such drainage district, but in no event shall the total area added by the county court be more than 50 percent of the area of the drainage district. [Amended by 2003 c.802 § 101]