Within thirty days after the filing with the secretary of state of the certified copy of the order of formation, a governing board of trustees for the district shall be appointed. The district board shall be appointed as follows:

(1) If the district is situated in one county only and consists wholly of unincorporated territory, five members shall be appointed by the county commissioners of the county.

(2) If the district is situated entirely in one county and includes both incorporated and unincorporated territory one member shall be appointed from each commissioner district lying wholly or partly within the district by the county commissioners of the county, and one member from each city, the whole or part of which is situated in the district, by the governing body of the city; but if the district board created consists of less than five members, the county commissioners shall appoint from the district at large enough additional members to make a board of five members.

(3) If the district is situated in two or more counties and is comprised wholly of incorporated territory, one member shall be appointed from each commissioner district of each county or portion of a county situated in the district by the county commissioners; but if the district board created consists of less than five members, the county commissioners of the county in which the greater area of the district is situated shall appoint from the district at large enough additional members to make a board of five members.

(4) If the district is situated in two or more counties and consists of both incorporated and unincorporated territory, one member shall be appointed by the county commissioners of each of the counties from that portion of the district lying within each commissioner district within its jurisdiction; and one member from each city, a portion of which is situated in the district by the governing body of the city; but if the board created consists of less than five members, the county commissioners in which the greater area of the district is situated shall appoint from the district at large enough additional members to make a board of five members.