Big Marsh is the largest wetland complex in the Calumet Region. A water control structure was installed in 2015 to control water levels and establish hemi-marsh conditions. The water control structure, along with removal of invasive species, has resulted in the reemergence of the bird population at Big Marsh. Birds are coming back in abundance, including a pair of yellow headed blackbirds, a species which has not been observed at Big Marsh for more than twenty years.
Its open water attracts a myriad of waterfowl, and the marshy portions have provided nesting habitat for Pied-billed Grebes, Least Bitterns and Common Moorhens. Sandpipers and herons of numerous species can be easily observed foraging on mudflats exposed by low water levels. For several years, the state’s largest Black-crowned Night Heron colony inhabited the marsh; given the nomadic nature of the species and changing environmental conditions, they may locate here again.