Wis. Admin. Code Department of Natural Resources NR 21.07
Buildings, vehicles, tents, fish shanties or similar enclosures may be used on the ice for fishing purposes on the Mississippi river, Lake St. Croix, the St. Croix river and St. Louis river as defined in s. NR 21.02(39) from the time the ice forms; provided, however, that all such enclosures or shelters shall be removed from the ice on or before March 1 of each year. The door of any such enclosure or shelter must be equipped with a latch which will permit the door to be readily opened from the outside at all times while the enclosure or shelter is occupied. Fishing shelters that are not occupied or otherwise in use shall have the name and residential address of the person owning such shelter or enclosure painted or permanently affixed in the English language on the outside of the structure with lettering a minimum of one inch square. Residents of Wisconsin or Minnesota angling from a fish house shall comply with the law of their respective states relative to licensing and identification of fish houses. Residents of states other than Wisconsin and Minnesota who hold a nonresident fishing license from either state must comply with the law of the issuing state relative to the licensing and identification of fish houses.
Wis. Admin. Code Department of Natural Resources NR 21.07