Wis. Stat. § 92.12: Intergovernmental cooperation.

Counties, cities, villages, towns and public agencies with natural resource responsibilities in the same or different counties may cooperate in carrying out the purposes of this chapter. If a problem of soil or water conservation is defined in part by drainage basin boundaries beyond a single county’s borders or otherwise transcends these borders, the respective counties, cities, villages, towns and public agencies with natural resource responsibilities may enter into mutually binding agreements and contracts containing, but not limited to, provisions for mutually enforced and administered regulatory ordinances and cost-sharing distribution arrangements.