From Minnesota's Department of Natural Resources (DNR):
Minnesota’s ice fishing shelter removal dates are approaching, and dark houses, fish houses and portables must be off the St. Croix River no later than midnight on March 1. Enforcement action will be taken if shelters are left after the deadlines.
Those not removing shelters will be prosecuted. Conservation officers may remove the structure and confiscate or destroy it. It is also unlawful to store or leave a shelter at a public access.
Anglers are advised to remove shelters earlier, if ice conditions warrant.
For inland waters, the shelter removal deadline is March 4.
After removal dates, shelters may remain on the ice between midnight and one hour before sunrise only when occupied or attended.
It is unlawful to improperly dispose of ice fishing shacks anywhere in the state. Anglers should check with local refuse providers or landfills for disposal.