When you imagine a dam, what comes to mind? Maybe it’s the hulking concrete wall of the Hoover Dam on the Colorado River or the Grand Coulee on the Columbia. Large barriers on large rivers, looming large on the horizon. But colossal structures like these make up only a fraction of the dams that chop up waterways across the United States. The nation’s rivers, streams and brooks are full of smaller dams — many of which aren’t monitored at the state or national level. And even though they’re small, these barriers can alter aquatic habitats and cause trouble for the species that live there. In this podcast, Madison Goldberg speaks with scientists about the issue and goes on a dam hunt of her own. Also find the full story on Scienceline's website: TK Music used: “Tower of Mirrors” by Blue Dot Sessions | CC BY-NC 4.0 “Copley Beat” by Blue Dot Sessions | CC BY-NC 4.0