Wis. Stat. § 198.21

Any provision of this chapter may be altered, amended or repealed at any time by the legislature, but no amendment, repeal or alteration shall ever be enacted which shall release any district from any liability which it shall incur for the acquisition of property or for obtaining funds for the purposes of the district. The guarantees of this section shall be a part of every contract authorized by this chapter and entered into by any district under this chapter.