Oregon Revised Statutes Cities § 223.327

A local government that imposes final assessments shall adopt an ordinance or other regulations establishing procedures for the equitable apportionment of final assessments under ORS 223.317 to 223.327. The ordinance or regulations shall authorize the local government to establish fees reasonably calculated to reimburse it for its actual costs in apportioning final assessments under ORS 223.317 to 223.327. The provisions of ORS 223.317 to 223.327 relating to apportionment of final assessments shall apply to estimated assessments with respect to any tract or parcel divided into smaller parcels prior to the levy of the final assessment.