Dams, like the one pictured above, can have detrimental effects on freshwater ecosystems and their connectivity. The dam above is the Prairie du Sac, which sits on the Wisconsin River, and fragments connections between the Wisconsin River and downstream Mississippi River (140 km downstream as the river flows). Changes in connectivity between the Wisconsin and Mississippi Rivers are driven primarily by changed water flows caused by damming. Changes in water flows have ‘knock-on’ effects on other processes that would naturally maintain connection between the Wisconsin and Mississippi Rivers. For example, larger bodied migratory fishes, such as different species of sturgeon that depend on both the Wisconsin and Mississippi Rivers can have more fragmented ranges because of changes in water flows and limited passage up- or down-stream of the dam. These changes in connectivity caused by damming can ultimately result in changes to migratory fishe species population structure, which can also drive species closer to extinction. My own connection to the Prairie du Sac dam stems from several visits and scientific research that explored stability of fish populations up- and down-stream of the dam. Despite my knowledge of the impacts that dams can have on freshwater ecosystems I am consistently blown away by the resources and human-power needed to construct this infrastructure and maintain it. Increasingly, government and non-government groups in the United States, Europe and Australia, are working to remove dams that have greater ecological and economic costs than benefits returned from maintaining the structures.
Haiku and photo: Steph Januchowski-Hartley