It continues winding through a wider valley alongside Route 30 to East Branch, where the East Branch's most significant tributary, the Beaver Kill, a world-renowned trout stream that rises in western Ulster County, flows in from the east. Here Route 30 ends at the Route 17 expressway, slowly being converted into Interstate 86, parallels the river, crossing back and forth. At the Hancock town line, the Blue Line turns to follow it south, taking the East Branch out of the Catskill Park. A few miles below that, at the village of Hancock, it turns south and joins the West Branch to create the Delaware's main stem.