The Great Lakes are strongly influenced by the river systems that are connected to them. Rivers are “the great collectors” of everything that happens on the land. Sediments, nutrients, chemicals, and just about anything else small enough to be carried by water can go from the land, to a river, and to our Great Lakes. For example, it has been determined that the equivalent of more than one dump-truck load of sediment flows into Green Bay from the Fox River each hour!
Freshwater estuaries are important for cleansing water on its way to the Great Lakes. When a river’s water reaches a freshwater estuary’s wetlands, nature’s filters go to work. Wetland vegetation and aquatic organisms can remove sediment and nutrients from the water column and transform and remove contaminants before they reach the Great Lakes.
The coastal wetlands in a freshwater estuary can function as flood storage, sediment traps, and water quality filters. For example, the Kewaunee River freshwater estuary wetland in Northeast Wisconsin traps 20% of the annual river sediment load before it reaches Lake Michigan. Similarly, studies in Ohio have found that the Old Woman Creek freshwater estuary decreases the annual load of phosphorus reaching Lake Erie. Freshwater wetlands have been found to have an approximate value of $594 per acre for flood control and $630 per acre for protecting water quality (based upon 2005 dollar values).
Sources of Additional Information:
Coastal Wetlands, State of the Lakes Ecosystem Conference Background Paper, 1997.
Economic Values of Saginaw Bay Coastal Marshes with a Focus on Recreational Values, Southwick Associates Inc., 2006.
Banner photos: Marsh marigold, red dogwood, swamp milkweed - Jeff Strobel.
Page photos: Mink River estuary - Jeff Strobel; Bark Bay -Patrick Robinson.
For more information about this site contact Patrick Robinson, Environmental Restoration Specialist, at patrick.robinson@ces.uwex.edu
Website developed and maintained by the Environmental Resources Center
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