Whenever there shall be a change in population in any of the nine districts heretofore established, evidenced by a federal census of population published following the last federal census of population preceding the adoption of this part, or by virtue of a change in the corporate limits, there shall be a reapportionment of the council districts in the manner hereinafter provided:
(1) The mayor shall within six months after the publication of each federal census of population for the city, following the last federal census of population preceding the adoption of this part, or if within six months after there shall have been any change in the corporate limits of the city, file with the council a report containing a recommended plan for reapportionment of the council district boundaries to comply with the following specifications:
Each district shall be formed of contiguous and to the extent reasonably possible, compact territory, and its boundary lines shall be the center lines of streets or other well-defined boundaries. b. Each district shall contain as nearly as is reasonable the same population. (2) The report shall include a map and description of the districts recommended and shall be drafted as a proposed ordinance and considered by the council as other ordinances are considered. Once filed with the clerk, the report shall be treated as an ordinance introduced by a council member.
(3) The council shall enact a redistricting ordinance within six months after receiving such report. If the council fails to enact the redistricting ordinance within six months, the redistricting plan submitted by the mayor shall become effective without enactment by the council, as if it were a duly enacted ordinance.
(4) The redistricting ordinance shall not apply to any primary or regular or special election held within six months after its becoming effected. No incumbent councilman or member of the board or commission shall be deprived of his or her unexpired term of office because of such redistricting.