Mich. Comp. Laws § 280.382

Sec. 382. Upon receiving such petition and certificate aforesaid, the judge of probate shall, within not less than 15 days, appoint a disinterested commissioner of an adjoining or nearby county to make the apportionment of benefits on said drain. It shall be the duty of said disinterested commissioner, so appointed, to make and complete within a period of 30 days, or within such reasonable time thereafter as may be necessary, an apportionment of the benefits of said drain and file the same with the said disqualified commissioner, and said apportionment shall be adopted for said drain, subject to the same rights of appeal as provided in this act. Said disqualified commissioner shall furnish the commissioner so appointed with a copy of his final order of determination on said drain.