Illinois State Museum

A fresh-water ecosystem consists of all the interacting living and nonliving entities in a body of fresh water. It includes interactions among sunlight, atmosphere, water, land, plants, and animals. It can be defined for a small stream, large river, lake, or pond.

Human Interactions
People have dammed and dredged rivers to make them navigable, built levees to control flooding, and drained backwater lakes to create agricultural lands. These changes and human uses of the land in the surrounding watershed affect fresh-water ecosystems in many ways.