From the Wisconsin State Journal:

With its swift currents, shifting sand bars and undeveloped shoreline, the Lower Wisconsin River is the longest free-flowing river in the Midwest, snaking more than 92 miles from the Prairie du Sac dam to the Mississippi River. It is also one of the most ecologically diverse, providing habitat for 98 species of fish, including rare species like longnose gar, grass pickerel and the paddlefish[…]But as temperatures rise, the river is increasingly under threat of invasion. If climate change is left unchecked, the Lower Wisconsin and more than half a dozen other rivers could become breeding grounds for invasive carp within a generation, according to a new study.