Due to development and hardening of the landscape, the rivers and streams of Cook County are much wider, faster, straighter and dirtier than they once were. Yet in some places, forest preserves help reduce runoff and erosion into the rivers, contributing to healthier systems with native fish, mammals, birds, mussels and insects. The Forest Preserves is helping to remove dams from rivers to restore historic water flows and encourage natural fish migrations.
Rivers. Three major rivers flow through the Forest Preserves of Cook County: the Chicago River, Des Plaines River and Little Calumet River. Forest preserves line a majority of the upper Des Plaines, as well as the North Branch of the Chicago River.
Streams. A number of smaller streams wind through forest preserves, including Salt Creek, Poplar Creek, Thorn Creek, Crooked Creek and Tinley Creek.
Read more about the ecosystems of the Forest Preserves of Cook County: