Wis. Stat. § 279.17: Trust funds.

All moneys received by the authority, whether as proceeds from the sale of bonds or as assessments or fees, shall be considered to be trust funds to be held and applied solely as provided in this chapter. Any officer with whom, or any bank or trust company with which, those moneys are deposited shall act as trustee of the moneys and shall hold and apply the moneys for the purposes of this chapter, subject to any regulations that this chapter and the bond resolution authorizing the bonds of any issue provide.