Mich. Comp. Laws § 324.4711
If territory that is part of a district created under this part is detached from a municipality and transferred to a municipality that is not part of the district, the territory shall remain a part of the municipality from which detached only for the purpose of carrying out any contractual obligations or for the purpose of levying a tax to retire any bonded indebtedness incurred by such district for which the territory is liable until the contractual obligations are fulfilled or the bonds are redeemed or sufficient funds are available in the district's debt retirement fund for this purpose. A territory described in this section is a part of the municipality to which transferred for all other purposes and subsequent to the redemption of the bonds or the time when sufficient funds are available to redeem the bonds, the territory is no longer a part of the district.
MCL 324.4711