Mich. Comp. Laws § 121.23: Authority; change in municipal jurisdiction.

Sec. 23.

No change in municipal jurisdiction over any territory within an authority shall affect in any manner the authority or its boundaries. If a new city is incorporated from a township in the authority, then the new city shall be deemed to be a part of the authority, and a constituent municipality thereof. No change in the jurisdiction over any territory in any city, village or township which has contracted to purchase water from the authority pursuant to the provisions of section 10 of this act, shall impair in any manner the obligations of the contract, but the same shall be carried out, insofar as such territory is concerned, by the authority and the municipality as shall have jurisdiction to furnish water to the territory.