ORS § 201.160
The boundary of Jefferson County is as follows: Beginning at the southeast corner of township 11 south, range 19 east of Willamette Meridian; running thence in a westerly direction along township lines to the northwest corner of section 4, township 12 south, range 16 east of the Willamette Meridian; thence in a southerly direction along section lines to the southwest corner of section 33, township 12 south, range 16 east; thence in a westerly direction along township lines to the southwest corner of township 12 south, range 15 east; thence in a southerly direction to the southwest corner of township 13 south, range 15 east; thence in a westerly direction along township lines to the summit of the Cascade Range; thence northerly along the summit of the Cascade Range to the projection westerly of the township line between townships 8 and 9 south; thence easterly along such projection and along the township line between townships 8 and 9 south to the intersection of such township line and the middle of the main channel of John Day River; thence up the main channel of John Day River to a point where such main channel intersects the east line of section 25, township 9 south, range 19 east; thence south on the east line of range 19 east to the point of beginning.
ORS 201.160