The Horn drains to the northeast into Redington Stream, then into the South Branch of the Dead River, the Kennebec River, and into the Gulf of Maine. The Horn drains to the west into Saddleback Lake, then into Redington Stream. The Horn drains to the south into Winship Stream, then into Conant Stream, Orbeton Stream, and the Sandy River, another tributary of the Kennebec. The Horn drains to the southeast into Hardy Stream, then into Orbeton Stream.