Wis. Stat. § 231.14: Trust funds.

All moneys received under the authority of this chapter, whether as proceeds from the sale of bonds or as revenues, shall be deemed 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, such moneys are deposited shall act as trustee of such moneys and shall hold and apply the same for the purposes of this chapter, subject to such regulations as this chapter and the bond resolution authorizing the bonds of any issue provide.