From TNT to Tallgrass
Before it was a prairie, this land was the Joliet Army Ammunition Plant. Opened in 1940, the facility was a combination of the Elwood Ordnance Plant and the Kankakee Ordnance Works, which together produced billions of rounds of ammunition and over one billion pounds of TNT for World War II, the Korean War, and the Vietnam War. At its peak during WWII, the plant employed over 10,000 people. Operations largely ceased by the late 1970s, and in 1993 the site was declared inactive.
The manufacturing and disposal practices left a legacy of contamination, including heavy metals and explosives in the soil and groundwater, leading to its designation as a Superfund site. The transformation began on February 10, 1996, when the Illinois Land Conservation Act established Midewin National Tallgrass Prairie, transferring the land from the U.S. Army to the USDA Forest Service. The name "Midewin" is a Potawatomi word for their society of healers. The conversion of this 18,500-acre industrial site into the nation's first national tallgrass prairie is a long-term ecological experiment.
The Science of Reconstruction
Restoring a ecosystem on degraded land is a meticulous process. It involves far more than simply planting seeds. Early efforts focused on removing old infrastructure, including hundreds of ammunition bunkers, 200 miles of roads, and agricultural drain tiles that altered the land's hydrology. The goal is to reestablish the natural processes that define a prairie. This includes planting a diverse mix of native species; the restoration plan involves at least 275 species of native pollinator plants. In some areas, like the 500-acre South Patrol Road Prairie, nearly 200 different plant species have already been introduced, with some grasses reaching 8 feet tall.
A central component of the restoration is the reintroduction of large herbivores. In October 2015, a herd of 27 American bison (Bison bison) was introduced to a 1,200-acre section of the prairie. This initial group consisted of four bulls and 23 cows. The bison are ecological engineers. Their grazing patterns differ from cattle, creating a mosaic of varied grass heights that benefits a wider range of grassland birds. Their wallowing creates depressions that can hold water, forming temporary wetlands for amphibians. Researchers are actively studying how the bison's natural behaviors influence plant diversity and soil health, providing data for other large-scale restoration projects.