This week we have a new Mainstreet Radio series, "Changing Currents." We'll look at a number of rivers and streams in our region. There are issues and challenges facing many of them. Our first few stories focus on the Mississippi. Over the last century the Army Corps of Engineers has transformed the Mississippi River. A series of locks and dams have made a reliable highway for commercial barge traffic. Many of the river's native species have suffered. None more so than the shrinking collection of fresh water mussels. The Army Corps wants to increase commercial river traffic. And the rush is on to save some species. Mainstreet Radio's Erin Galbally has the first installment of our series.