The Great Lakes Compact is an agreement between the states and provinces surrounding the Great Lakes basin where each member agrees to be a good custodian of the water resources on its doorstep. But what exactly does that mean? What happens when people outside the basin want some of that precious freshwater? And how can we protect the lakes from toxins and invasive species? Journalist Dan Egan and political economist Jenny Kehl take Steve Paulson through the finer points of the politics of water.