Not far from the actual fall, the stream created by the Rinka Waterfall vanishes deep into the rocky ground. These waters gush to the surface again on reaching the impermeable Werfen strata further down the valley, from where the stream emerges as the Crna ("Black") and flows over dark sedimentary clays that impart it with its black tincture. This stream then flows along a regulated riverbed to the lower end of the Logarska Dolina Valley where it has its confluence with the Jezera stream (which flows out from the neighbouring Matkov Kot Valley) from which point it becomes the Savinja. This source has been proclaimed as natural heritage.