Watch Confluence for Free: How to Stream the Movie Online at 123Movies. . The Lewiston / Clarkston valley has a rich history. It is here, at the confluence of the Clearwater and Snake Rivers, where Lewis and Clark camped on their westward journey over two hundred years ago. Residents boast that the valley is the gateway to Hells Canyon, that Lewiston was Idaho's first capital. However, the valley also has a much darker past, one that many know about, but few publicly acknowledge. From 1979 to 1982, five people disappeared. Only three of the bodies have ever been found. All share one suspect.