Well Abandonments are covered under Wisconsin's private well code, NR812 in NR812.26.
The DNR has grants available. Learn more and see if you qualify here.
Well abandonments may only be performed by licensed well drillers and licensed pump installers. The finished abandonment must be logged on form 3300-005 Form 3300-005 (R 4/08) and a copy sent in to the Department. You can view the form here.
The DNR maintains a comprehensive information base here. It is worth a look.