Over 32,000 acres in size, Horicon Marsh is the largest freshwater cattail marsh in the United States. The marsh provides habitat for endangered species and is a critical rest stop for thousands of migrating ducks and canada geese. It has been recognized as a Wetland of International Importance, a unit of the Ice Age National Scientific Reserve, and both a Globally and State Important Bird Area.
Horicon National Wildlife Refuge (21,000 acres) makes up the northern two-thirds of the marsh and is managed by the U.S. Fish and Wildlife Service. The sourthern one-third is administered by the Wisconsin Department of Natural Resources as the Horicon Marsh State Wildlife Area (11,000 acres). Both agencies work together to manage the marsh as one wetland ecosystem.
The U.S. Environmental Protection Agency is coordinating an interagency planning effort to better prepare for an oil or hazardous materials spill at the marsh, per the National Contingency Plan.
