ORS § 547.110
In the same month of each year after the election of the first board of supervisors, the board shall call a meeting of the owners of land in the district. The board shall give notice in the manner provided for in ORS 547.105. The owners shall meet at the time and place fixed by the board and elect one or two supervisors in the manner prescribed in ORS 547.105, who shall hold office for three years and until a successor is elected and qualified. However, after the report of the commissioners has been confirmed by the court under the provisions of ORS 547.235, only the owners, or the designees of the owners, of the land having benefits attributed to the land are entitled to vote at the annual meetings held under the provisions of this section.
ORS 547.110