Big Lake Butte des Morts () is an 8,800-acre lake located in the U.S. state of Wisconsin and is part of the Winnebago Pool. The lake is fed by the Fox River in the southwest and the Wolf River draining from Lake Winneconne in the northwest, and drains via the Fox River southeast into Lake Winnebago. The lake is also part of the Butte des Morts region in Winnebago County, Wisconsin.
Much of the lake is flooded marshland, which was created by the damming of the Fox River downstream in Menasha in the 19th century. This has resulted in the lake's flat and shallow character. U.S. Highway 41 / Interstate 41 spans the east end of the lake via a bridge and causeway combination. The bridge includes the Tribal Heritage Crossing, a designated national trail, which is a portion of the Wiouwash Trail. The city of Oshkosh lies between Lake Butte des Morts and Lake Winnebago.
Address 54904, United States
Coordinates 44°4'17.117" N -88°38'33.858" E