Oregon Revised Statutes Education and Culture § 334.032

(1) The board of directors of an education service district shall divide the education service district into not more than 11 zones as nearly equal in census population as may be practicable, measured along common school district boundary lines except that zones may be established using voting precinct boundaries in order to achieve greater equality of population. If possible, the board shall establish the zones so that each county within the education service district, the majority of the land area of which lies within the boundaries of the education service district, has at least one member on the board.

(2) Each county within the education service district, the majority of the land area of which lies within the boundaries of the education service district, shall have at least one member on the board or shall have at least one member on the budget committee of the education service district.

(3) The board may readjust the boundaries of the zones once each year and shall readjust the boundaries of the zones immediately upon any change of the boundaries of the education service district.