Abstract: This disclosure relates generally to spa waterfall lighting systems. A spa waterfall lighting system can include a waterfall body with a base portion and a top portion, and a wired light located within the waterfall body. A projection, coupling, or barb is in connection with the base portion of the waterfall body. The projection includes an externally threaded portion, with a channel formed in the externally threaded portion. The channel receives a wire, the wire in electrical connection with the wired light located within the waterfall body. A threaded nut secures the projection to a spa shell, and the threaded nut is threadable over the externally threaded portion of the projection when the wire is in the channel.