Mich. Comp. Laws § 280.572

Sec. 572. Public corporations may advance funds for the payment of any part of the cost of a project hereunder and shall be repaid by the district when funds are available therefor. The board is hereby authorized to assess preliminary costs in an equitable manner prior to the issuance of bonds, against public corporations within the district, to be assessed and collected as provided in section 567 of this act: Provided, That the percentage of such costs to be assessed against such public corporations shall be approved by the commission.