ORS 545.211

The number of directors may be decreased to three substantially in the same manner as that provided for the increase of directors. When the number of directors is decreased, the board shall redivide the district into three divisions. The existing board shall continue in office until the expiration or other termination of their terms. Successors shall be appointed or elected only in divisions where representation will terminate with the term of a director. Directors shall thereafter be appointed or elected only as necessary to fulfill the requirements of the decrease in membership of the board, and so that the term of one director will expire each year.