Horicon National Wildlife Refuge

At more than 33,000 acres, Horicon Marsh is one of the largest freshwater marshes in the United States and is a critical rest stop for thousands of migrating ducks and Canada geese. It is recognized as a Wetland of International Importance, as both Globally and State Important Bird Areas and is also a unit of the Ice Age Scientific Reserve. Located in Dodge and Fond du Lac counties, Horicon Marsh is fed by the Rock River which flows through the refuge following a course through southern Wisconsin and eventually ending in the Mississippi River at Rock Island, Illinois.

The northern two-thirds of Horicon Marsh is managed federally by the U.S. Fish and Wildlife Service as the 22,000 acre Horicon National Wildlife Refuge. The refuge was established in 1941 to provide an undisturbed sanctuary for a number of migratory birds and waterfowl including the redhead duck as well as to provide opportunities for people to connect with nature through many wildlife dependent recreational activities such as wildlife observation, photography, environmental education, interpretation, fishing and hunting. 

The southern third of the marsh, 11,000 acres, is managed by the Wisconsin Department of Natural Resources as Horicon Marsh State Wildlife Area. It was established in 1927.