The Fox-Wolf River Basin is located in east-central Wisconsin and has an area of 6,430 square miles (16,654 square kilometers). Contained within the basin is the Wolf River, the Upper Fox River, the Lake Winnebago pool and the Lower Fox River. The Lake Winnebago pool consists of Lakes Winnebago, Poygan, Winneconne and Butte Des Morts.
Lake Winnebago, located between the Upper and Lower Fox Rivers, is the largest inland lake in the state of Wisconsin. The level of Lake Winnebago is controlled by a federal dam at Menasha and a private dam at Neenah. At the elevation of the crest of the Menasha Dam, Lake Winnebago has a surface area of about 206 square miles (534 square kilometers), a length of about 28 miles (45 km), a width of about 10 miles (16 km) and a depth of about 21 feet (6 meters).
The Lower Fox River, connecting Lake Winnebago and Green Bay is 39 miles (63 km) long, with its width varying from about 400 (152 m) to 1,000 feet (305 m). The vertical drop from Lake Winnebago to Green Bay (Lake Michigan) is about 168 feet (51 m). In general, the river flows between high clay banks having frequent reaches of exposed limestone and an average slope of about 5 feet (1.5 m) per mile. Several cities are located along the Lower Fox River. Most of the land along the river bank has been highly developed for uses such as paper mills, power plants and other related purposes. The remainder of the drainage basin below Lake Winnebago is well-developed agricultural land.
Nine federal dams and four non-federal dams are located along the Lower Fox River. The nine federal dams are owned and operated by the U.S. Army Corps of Engineers, Detroit District. The locks associated with these dams were turned over to the state of Wisconsin in 2005.