Mich. Comp. Laws § 280.528
The drainage board may issue 1 or more series of bonds for and on behalf of the drainage district, in anticipation of the collection of any or all installments of assessments, and pledge the full faith and credit of the drainage district for the prompt payment of the principal of and interest on the bonds. The bonds shall mature or be subject to mandatory redemption with the last maturity not later than 2 1/2 years after the due date of the last installment of the assessments and there may be more than 1 principal maturity or mandatory redemption date during any 12-month period. The bonds shall be signed by the chairperson and secretary of the drainage board, who shall cause their facsimile signatures to be affixed to the interest coupons attached thereto. Collections of both principal and interest on all installments of assessments in anticipation of which bonds shall have been issued shall be kept in a separate bank account by the treasurer for the drainage board and used for no other purpose than the payment of principal and interest on the bonds until the full payment of the principal and interest on the bonds.
MCL 280.528