Michigan Compiled Laws, Chapter 324. Natural Resources and Environmental Protection § 324.34137

Sec. 34137. (1) Except as prescribed in subsection (2), the final order of determination, the order of apportionment of benefits, or the order confirming the special assessment roll shall not be subject to attack in a court except by proceedings by writ of superintending control brought within 20 days after the filing of the order in the office of the chairperson of the irrigation board issuing the order. If a proceeding is not brought within the time prescribed, the irrigation special assessment district and project shall be considered to have been legally established, and the legality of the irrigation special assessment district and project and the assessments for the district and project shall not be questioned in an action at law or in equity.

(2) This section shall not prohibit the bringing of an action pursuant to the open meetings act, Act No. 267 of the Public Acts of 1976, being sections 15.261 to 15.275 of the Michigan Compiled Laws.