The Bad River is a river flowing to Lake Superior in northern Wisconsin in the United States. It flows for 119.6 kilometres (74.3 mi) in Ashland County, draining an area of 1,061 square miles (2,750 km2) in portions of Ashland, Bayfield and Iron counties. The Bad River sloughs were designated a Ramsar Wetland of International Importance on February 2, 2012.