The northern two-thirds of Horicon Marsh is managed by the U.S. Fish and Wildlife Service as the 22,000 acre Horicon National Wildlife Refuge. The southern third of the marsh, 11,000 acres, is managed by the Wisconsin Department of Natural Resources as Horicon Marsh State Wildlife Area. 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.
Horicon National Wildlife 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 mission of the National Wildlife Refuge System is to administer a national network of lands and waters for the conservation, management and, where appropriate, restoration of the fish, wildlife and plant resources and their habitats within the United States for the benefit of present and future generations of Americans.
Everywas created for a special purpose. Some were created to protect migratory birds, others to protect threatened or endangered species or unique habitats, while others fulfill another special purpose. All activities allowed on refuges must be evaluated to make sure each activity will not conflict with the reason the refuge was founded.
Horicon National Wildlife Refuge was established to provide undisturbed habitat for migrating birds - most notably the redhead duck. Horicon attracts the largest breeding population of redhead ducks east of the Mississippi River. Portions of the refuge were also set aside so that visitors could enjoy the wildlife and habitat via hiking trails and other outdoor recreation facilities.
The Migratory Bird Hunting and Conservation Act uses money from Duck Stamp sales to purchase refuge lands. Many lands purchased with Duck Stamp funds were defined as inviolate sanctuaries. These lands, under most circumstances, must be at least partially closed to migratory bird hunting to allow birds a place of refuge and protection where they cannot be harmed.
1927 - Horicon Marsh State Wildlife Area is established.
1934 - Horicon Dam operational (WI DNR).
January 23, 1941 - Horicon National Wildlife Refuge is established.
1948-1952 - Main Dike Road/Weir installed.