The extensive freshwater wetlands of the Great Lakes' coasts are unique in ecological character, size and variety. They range from small wetlands nestled in scattered bays to extensive shoreline wetlands such as those of southwestern Lake Erie, freshwater estuaries such as the Kakagon Sloughs of northern Wisconsin and the enormous freshwater delta marshes of the St. Clair River. Found between the areas of dry land and open water, they include marshes , swamps , bogs , fens and barrier beach wetlands. Differing from inland lakes, wetlands are shaped and influenced by waves, seiches , and lake level fluctuations.
Wetlands are one of the most productive ecosystems in the world, being home to many rare species.
The U.S. Fish and Wildlife Service estimates that 43 percent of all threatened and endangered species rely on wetlands for their survival. Wetlands are an important part of the migratory cycle, providing food, resting stops and habitats for many migratory birds, such as ducks and geese. Wetlands also improve water quality by slowing surface runoff , and processing organic waste and sediments before they reach open water, thus protecting aquatic life and sources of drinking water. Flooding is also controlled with the help of wetlands. Wetlands will store water during times of flood or high lake levels, and then will slowly release the water during times of drought or low lake levels.