ORS § 451.590
Officers and employees of a county or of a district may enter upon privately owned lands to survey or lay out service facilities by direction of the county court or governing body of the district. However, the county court or governing body of the district shall cause notification to be given to each occupant of the lands, either by registered or certified mail or by other lawful means. This notice shall be given at least five days before the county or district officers or employees enter upon the lands. No officer or employee of a county or district entering privately owned lands pursuant to this section shall damage or destroy trees, shrubs, buildings or other items of value on that land without first obtaining the consent of the owner.
ORS 451.590