War on invasive plants

restores a famous bog

Removing invasive plant species and restoring the natural flow of water is restoring natural functions and creating new fish and wildlife habitat at the Cowles Bog wetland complex, a nationally recognized natural feature along the Lake Michigan coast, near Chicago.


The Cowles Bog Wetland Complex is comprised of 205 acres of land at the western terminus of what was once known as the Great Marsh. Formed about 4,000 years ago, the Great Marsh was an open body of water comprised of one watershed, which flowed to Lake Michigan through Dunes Creek. Over time the Great Marsh evolved from an open water body to a diversity of wetland types inclusive of conifer swamp, wet prairie, fen, bog, sedge meadow and marsh. Urbanization and commercial development changed the wetland complex from an area rich in plant diversity to one overrun by non-native cattail and other invasive plant species that ruined fish and wildlife habitat. The Indiana Dunes National Lakeshore is working to restore the Cowles Bog Wetland Complex to increase native plant and animal diversity, create more habitat, protect the beaches and improve Lake Michigan’s water quality by reducing and controlling polluted runoff. Fully restoring this large ecosystem will take 10 to 15 years.

Resource Challenges Addressed

  • Invasive species
  • Loss of fish and wildlife habitat
  • Low nearshore water quality


Monarch butterfly on swamp milkweed

Native plants, such as the swamp milkweed pictured above, are beginning to return to Cowles bog. Credit: Edward Boggess U.S. Fish and Wildlife Service.

Results and Accomplishments

To date, crews have restored 55 acres of Cowles Bog by replacing invasive plants with native species and restoring natural water flow in the marsh, which filters pollutants out of surface water before it flows into Lake Michigan.