Michigan Compiled Laws, Chapter 280. Drain Code of 1956 § 280.624

Sec. 624. Actions heretofore taken by a drainage district or a public corporation and bonds heretofore issued under this act as originally adopted or subsequently amended are hereby validated. A district acting under this act as originally adopted or subsequently amended, or a public corporation shall not contest the validity of any bonds or any assessment which provides the security therefor or any action taken by the district or public corporation after the bonds are sold and delivered and consideration therefor is received.