It would flood certain parts of the land and dry out other parts. It will kill some water animals that are in the river and also destroying plants. If by chance there is a village well guess what it will be flooded. But the good news is that the beavers will have a home, the only other problem is that when it floods the forest it will drown many animals that can't escape it. It might even kill other unknown species!!! So if beavers build a dam there we will lose a lot.
