Oregon Revised Statutes Revenue and Taxation § 308.207

(1) If the taxing or bonding power of any governmental unit is limited to a millage or percentage of the real market value of the taxable property within the unit, the real market value shall be the real market value as reflected in the last certified assessment roll.

(2) Changes in the boundary lines of a governmental unit shall be taken into account in computing its real market value for purposes of subsection (1) of this section even though such boundary changes may not be included on the latest assessment roll.

(3) As used in this section, “governmental unit” includes the state, counties, cities, municipal corporations, and all special districts having the power to levy taxes or issue bonds.