Question: What tributary enters the Clinch near the former site which goes by the codename given it by the Manhattan Project during World War II for the project to produce enriched uranium for atomic bombs using the gaseous diffusion method?
Sentence (from "Poplar Creek (Tennessee)"): Draining a watershed area of more than 82 mi2 , it enters the Clinch near the former K-25 site, a short distance downstream from the confluence of East Fork Poplar Creek, its largest tributary.
Relevant evidence: Yes