Great Marsh Restoration Reduces Basement Flooding

Improves Wildlife Habitat

Removing a ditch system and invasive plants around Indiana’s Great Marsh has improved Lake Michigan’s water quality, improved wildlife habitat, and reduced flooding in people’s basements.

Description

Located just south of Lake Michigan in the Indiana Dunes National Lakeshore, the Great Marsh provides crucial wetland habitat for a variety of native wildlife and plants. Migratory birds such as the sandhill crane rely on the Marsh for nesting sites. The Great Marsh also plays a critical role in filtering out nutrients and other pollutants from stormwater runoff, preserving the water quality of Lake Michigan. Yet despite its ecological importance the Great Marsh has been significantly altered by centuries of human activities. Developers in the 19th century constructed a series of ditches to drain the Great Marsh, converting much of its wetlands to other land uses such as agriculture and industry. The ditch system divided the Great Marsh watershed into three distinct watersheds, fragmenting its wetland habitat and disrupting its natural hydrology. This has reduced the ability of the Great Marsh to absorb stormwater, increasing the flow of polluted runoff into Lake Michigan and increasing basement floodings in nearby communities. Altering this ecosystem has also allowed trees and invasive plants such as hybrid cattail and reed canary grass to displace native plant communities, degrading the habitat quality of the Great Marsh.

Thanks to a grant from the Great Lakes Restoration Initiative, the National Park Service is restoring the Great Marsh ecosystem. Workers removed much of the existing ditch system by filling the ditches with soil, and by plugging culverts draining the Marsh. Workers then removed trees and invasive plants that had colonized the Great Marsh to allow a more healthy and natural ecosystem to develop. Workers replaced the invasive with native plants, and dispersed seeds from other areas of the park to reestablish a native seed bank. Removing the ditch system has partially restored the marsh’s natural hydrology and increased its ability to absorb more stormwater runoff and filter out pollutants, significantly improving Lake Michigan’s water quality. It has also decreased the frequency of basement flooding during storms by drawing excess water into the wetland site. Removing the trees and invasive plants has promoted a healthier ecosystem, greatly increased habitat availability and quality for aquatic wildlife communities.

Resource Challenges Addressed

  • Habitat fragmentation
  • Invasive species
  • Polluted storm runoff
  • Flooding
  • Lack of suitable aquatic habitats

GREAT MARSH RESTORATION

Indiana dunes

Indiana Dunes National Lakeshore. Credit: National Park Service, M. Woodbridge Williams

Results and Accomplishments

This project has restored or enhanced 600 acres of wetlands in the Great Marsh. Removing the ditch system has partially restored the Marsh’s natural hydrology and increased its ability to absorb stormwater runoff and filter out pollutants, significantly improving Lake Michigan’s water quality. It has also decreased the frequency of basement flooding during storms by drawing excess water into the wetland site. Native birds such as sandhill cranes, great egrets, herons, and a variety of waterfowl are beginning to return to their natural nesting sites. This has significantly enhanced recreational opportunities for wildlife watchers.