ORS § 547.485
In case of neglect or refusal of the board of supervisors to cause such assessment and levy to be made, the assessment and levy shall be made by the governing body of the county in which the office of the board of supervisors is situated, sitting for the transaction of county business, in the same manner that the court or board levies county taxes. The levy and assessment shall contain the apportionments and description of ownership holdings of each person assessed in the same manner as provided in ORS 547.475 and shall be certified to the assessor not later than July 15 in the manner provided in ORS 310.060. All expenses incident thereto shall be borne by the district. The levy and assessment shall be entered on the county tax roll by the county assessor in the manner provided in ORS 547.475.
ORS 547.485