If the ballot proposition receives majority voter approval, the size of the board of county commissioners shall be increased to five members as provided in this section.

The two newly created positions shall be filled at elections to be held in the next year. The county shall, as provided in this section, be divided into five commissioner districts, so that each district shall comprise as nearly as possible one-fifth of the population of the county. No two members of the existing board of county commissioners may, at the time of the designation of such districts, permanently reside in one of the five districts. The division of the county into five districts shall be accomplished as follows:

(1) The board of county commissioners shall, by the 90th day prior to the first day of the filing period described in RCW 29A.24.050 of the year following the election, adopt a resolution creating the districts;

(2) If by the 89th day prior to the first day of the filing period described in RCW 29A.24.050 of the year following the election the board of county commissioners has failed to create the districts, the prosecuting attorney of the county shall petition the superior court of the county to appoint a referee to designate the five commissioner districts. The referee shall designate such districts by no later than the 60th day prior to the first day of the filing period described in RCW 29A.24.050 of the year following the election. The two commissioner districts within which no existing member of the board of county commissioners permanently resides shall be designated as districts four and five.