Wis. Stat. § 231.11: State pledge.

The state pledges to and agrees with the holders of any obligations issued under this chapter, and with those parties who may enter into contracts with the authority under this chapter, that the state will not limit or alter the rights vested in the authority by this chapter until such obligations, together with the interest thereon, are fully met and discharged and such contracts are fully performed on the part of the authority, but nothing shall preclude such a limitation or alteration if adequate provision is made by law for the protection of the holders of such obligations of the authority or those entering into such contracts with the authority.