Wis. Stat. § 229.853: Trust funds.

All moneys received by the district under this subchapter, whether as proceeds from the issuance of bonds or the incurrence of other debt or as revenues, shall be considered to be trust funds to be held and applied solely as provided in this subchapter. Any officer with whom, or any bank or trust company with which, the moneys are deposited shall act as trustee of the moneys and shall hold and apply the same for the purposes of this subchapter, subject to such regulations as this subchapter and any bond resolution or debt agreement authorizing the bonds or debt may provide.