Walking the Canal towpath towards Georgetown, one comes across a sign that is literally almost in the Potomac River, reading in urgent letters, “Deadly undertow, Get to shore.” But this undertow is only one of the Potomac’s lethal actions; it is also capable of serious flooding causing immense damage. In fact, it was a series of such floods that propelled the Chesapeake and Ohio Canal to change course, from its historic role of commercial transport to one of becoming a conduit for wildlife, and entering the National Park System as a National Historical Park.