When lands are entered upon under section 5543.12 of the Revised Code, the county engineer shall agree with the owners of such lands, subject to the approval of the board of county commissioners or board of township trustees, as to the amount of compensation and damages already sustained or to be sustained by such owner, and the amount of such compensation and damages, so determined, shall be paid by the county or townships.
If the engineer is unable to agree with such owner upon the amount of compensation and damages already sustained or to be sustained, such amount shall be determined in accordance with sections 163.01 to 163.22, inclusive, of the Revised Code.
R.C. §5543.13