Wis. Stat. § 200.07: Dissolution.

If a district has been inactive for at least 2 years and if the department receives certified copies of a resolution recommending the dissolution of the district adopted by the governing bodies of every municipality owning or operating the district, upon a finding that all outstanding indebtedness of the district has been paid and all unexpended funds returned to the municipality which supplied them, or that adequate provision has been made therefor, the department shall either order or deny dissolution of the district.