Oregon Revised Statutes Highways, Roads, Bridges and Ferries § 371.353

The district board of a special road district located in a county of between 3,000 and 3,500 square miles and with a population of between 100,000 and 200,000 may seek elector approval to divide the district into zones for the purpose of imposing and levying property taxes at a different rate and amount on the assessed value of all taxable property in each zone. The establishment of zones within a district under ORS 371.353 to 371.357 must be based upon and reflect qualitative differences in the services provided by the district to the residents and their property in each zone.