The commission by resolution may, and upon petition signed by not less than two hundred fifty (250) electors residing in the area to be redistricted, shall, re-establish the boundaries of the commissioner districts in that portion of the port district which is in the county in which the district was initially formed, so that each such commissioner district shall comprise as nearly as possible one-third (1/3) of the population of so much of the port district as is within such county, provided that no county voting precinct shall be divided by the boundary lines of a commissioner district.