When water is left alone, it makes a mess. It backs up into wetlands. Rivers overflow their banks. Mud and silt builds up, new channels open up. But Elijah Portugal, who studies how rivers and streams shape the land, says that that mess is what rivers need to be functional. “Messiness matters,” he says. In this program, we’ll meet some of the people who have been responsible for cleaning up rivers: the state and federal agencies responsible for controlling water -- for making sure it doesn’t