Coordinates: 48°03?35?N 114°04?51?W? / ?48.05972°N 114.08083°W? / 48.05972; -114.08083 The Swan River starts in the Mission Mountains at Grey Wolf Lake and continues north to Swan Lake. Then it goes west and over a dam into Bigfork Bay and the town of Bigfork where it enters Flathead Lake. It is a moderately sized river, having carved the Swan Valley.