Complex sentence: The largest city on the waterfront is Lake City, Minnesota, though the wide area stretches from Bay City, Wisconsin in the north down just past Pepin, Wisconsin in the south, just upstream from where the Chippewa River enters the Mississippi.
Split into simpler sentences: The largest city on the waterfront is Lake City, Minnesota. The wide area of the lake stretches from Bay City, Wisconsin, in the north, down past Pepin, Wisconsin, in the south, with Pepin being just upstream from where the Chippewa River enters the Mississippi.