Mich. Comp. Laws § 324.34126
After the hearing, the irrigation board shall enter its final order of apportionment and order of confirmation of the roll and shall make an endorsement upon the roll showing the date of confirmation and when the amount to be raised is to be payable. If the amount is to be payable in more than 1 installment, the irrigation board shall enter on the roll a memorandum of the installments and of the years when the installments shall be spread and shall add a certificate in writing of the determination whether the taxes assessed for benefits shall be paid in 1 or more years. The special assessment rolls shall be dated and signed by the irrigation board and filed on or before the last Wednesday in September of each year in the office of the county clerk of the counties involved. When any improvement special assessment roll is confirmed by the irrigation board, it shall be final and conclusive.
MCL 324.34126