Another, less well known, place where the two systems can come into contact is Eagle Marsh, west of Fort Wayne, Indiana. The Little River, a Wabash River tributary, and the Saint Marys River, a Maumee River tributary both abut a wetland preserve where their waters can comingle during floods that are increasingly frequent on both.
It's not so much a route for pollutants to flow from one system to the other, as it is a possible route for Asian carp that already infest the Wabash to find their way to Lake Erie. To reduce that likelihood, the Corps of Army Engineers in October, 2010, completed a mesh barrier fence across the area that is intended to prevent the migration of carp during high water. The fence is intended as an interim measure until a more permanent solution can be devised. It's designed to restrain adult fish, as juveniles are thought unlikely to be able to migrate that far upstream.
http://www.journalgazette.net/articl...GS01/100719773
http://www.lrwp.org/news.php#U-95