Mich. Comp. Laws § 280.481

Sec. 481. Unless otherwise provided by the drainage board, assessments against a township shall be against the township as a whole, including any incorporated village, but the drainage board may determine to assess separately or exclude a village, in which case the assessment against the township shall be exclusive of the village and the tax levies to be made by the township to pay the assessment shall not include property taxable in the village.