Mich. Comp. Laws § 560.165

Sec. 165. Within 15 days after the date of receiving the plat under section 161(2)(b), a majority of the board of county road commissioners shall do 1 of the following: (a) Approve the plat, instruct the chairperson to certify their approval on the final plat, and notify the proprietor of the board's approval. (b) Reject the plat, give their reasons in writing, and return it to the proprietor. The board of county road commissioners shall send a copy of the letter of rejection to the clerk of the governing body and the chairperson of the county plat board.