http://www.dnr.state.wi.us/fish/seasons/trout.htm

Exceptions

Not all Wisconsin waters follow the fishing season dates for a species for general inland waters or boundary and outlying waters. Exceptions do exist! You must consult the special county regulations in the current hook and line or trout regulations guides, as appropriate, to determine if any special season dates exist for the particular waters you plan to fish. This is the only way to determine whether or not the waters you plan to fish follow the season dates for general inland or boundary and outlying waters listed below. Unless noted otherwise, the dates listed are for the hook and line harvest of fish, not catch and release. Dates are inclusive.

You must also consult the current Trout Fishing regulations for information concerning bag and minimum length limits for a species.