In my opinion, based on my interpretation of the MN Fishing Regulations on page 51 under Border Waters – Wisconsin – Minnesota, there is not such thing as MN or WI side of the river. Here is the regulation – you read it and tell us what you think:
“Wisconsin – Minnesota: The seasons and regulations listed below apply to the following waters: Mississippi River (downstream of Prescott, Wisconsin and all waters between the Burlington Northern (Wisconsin) and Chicago Milwaukee (Minnesota) railroad tracks), Lake Pepin, St Croix River, Lake St Croix, St Louis River, St Louis Bay, and Superior Bay.”
In addition you should read the Border Waters regulations on Page 43. It states:
Minnesota has a reciprocal agreement with each of its bordering states: Wisconsin, Iowa, South Dakota and North Dakota. Residents of Minnesota or a bordering state may fish throughout the waters bordering the two states only if they possess a valid resident license from their resident state. Nonresident anglers who have a nonresident license from either Minnesota or the bordering state may also fish throughout the border waters between the two states. Anglers may launch and fish from either shore and may transport their catch by the most direct route to the state in which they are licensed.”