ORS § 545.424
When the assessments were made substantially in accordance with ORS 545.381, 545.385, 545.387, 545.389, 545.391 and 545.413, all assessments made before May 24, 1933, against real property within any irrigation district by the board of directors of the district are hereby validated. The assessments shall be a lien upon the real property described in the assessment, notwithstanding that the assessments were not entered on the county assessment roll against the property described as provided by ORS 545.420. Any assessment levied against lands partly within and partly outside the boundaries of any irrigation district shall not be void because the lands are partly outside the district, but shall constitute a valid assessment against that portion of the lands described in the assessment lying within the boundaries of the irrigation district.
ORS 545.424