Flathead Lake and the Salish: The Largest Natural Freshwater Lake West of the Mississippi

Flathead Lake, south of Kalispell in the Flathead Valley, covers nearly two hundred square miles and reaches a maximum depth of approximately three hundred seventy-one feet. It is the largest natural freshwater lake west of the Mississippi River by surface area.

The lake sits within the aboriginal territory of the Salish people, whose name for the region is reflected in the river, the valley, and the forest that carries their anglicized designation. The Salish were not, historically, a lake-dwelling people in the sense of building permanent settlements at its shores; they were a mobile hunting and gathering society that moved between seasonal resource sites. The lake and its tributaries were fishing grounds, and the Flathead River that drains it was a travel corridor.

The Confederated Salish and Kootenai Tribes of the Flathead Reservation were established by the Hellgate Treaty of eighteen fifty-five, which compressed the traditional territory significantly onto a reservation that included the southern half of Flathead Lake. The northern half of the lake, for many decades, was in federal public ownership. A series of legal agreements over the twentieth century returned the full lake to tribal jurisdiction; the current status is that the Confederated Salish and Kootenai Tribes own the lakebed and regulate fishing through tribal permits.

The Flathead National Forest surrounds the lake on the east and north. The Mission Mountains Wilderness, a range visible from the lake's eastern shore, is one of the few wilderness areas with specific tribal management provisions, including seasonal closure of some areas to all non-tribal visitors to protect ceremonial and subsistence activities.