Upper Mississippi National Wildlife & Fish Refuge - WI, IA, MN, IL

With 264 miles of shoreline, pools, islands and forests in four states (Minnesota, Wisconsin, Iowa and Illinois), this is the longest national wildlife refuge in the Lower 48. Similar habitats in the region have disappeared rapidly as a result of pollution and channelization of the once-meandering Mississippi, making this refuge essential habitat for tens of thousands of tundra swans, canvasback ducks and many other migrating birds each year. More than 160 pairs of bald eagles and 15 active Heron colonies nest on the refuge each spring.

The Threat

The refuge is susceptible to global warming because increased temperatures have led to more intense rain storms and flooding in the Upper Mississippi. Severe floods, such as those in 1993, 1996 and 2001, are now occurring more frequently. These floods erode islands, deposit blankets of sediment in backwaters, kill native bottomland hardwood trees and wipe out aquatic vegetation. If current trends continue, flooding and high water levels will disrupt the food chains that support birds and fish on the refuge, and could severely stress tundra swans, canvasback ducks and eagles.

The number of fish species found in a river decreases as the volume of water flowing through the river and thus, the river's available habitat space, declines. Scientists believe that climate changes and other processes that remove water from a river (such as irrigation) are and will continue to decrease the amount of water in the Upper Mississippi River Basin. Many fish, including lake sturgeon and paddlefish, that call the Upper Mississippi National Wildlife and Fish Refuge home can only survive in environments with high volumes of water and will be directly impacted by climate change.