Districts may be created for the purpose of undertaking a program of lake protection and rehabilitation of a lake or parts thereof within the district.
Wis. Stat. § 33.21
A district may rehabilitate part of a lake only if the entire lake lies within the district. Kaiser v. City of Mauston, 99 Wis. 2d 345, 299 N.W.2d 259 (Ct. App. 1980).