The
Crni Rzav (, ; "Black Rzav"), is the Rzav's longer headstream. It originates from the
Čigota mountain, eastern section of the
Zlatibor mountain. The river originally flows northward, next to the villages of Vodice and Jokina Ćuprija, reaches the central section of the Zlatibor where it is dammed and creates the artificial
Ribnica Lake (surface area of 10 km2), after the nearby village of Ribnica. The reservoir was formed in 1971. After the lake, the river sharply turns west and soon gets followed by the parallel stream of the
Jablanica river. After crossing the village of
Mokra Gora (hamlet Panjak) on the Serbian-Bosnian border Crni Rzav meets the Jablanica river at the village Gornje Vardište and finally the river Beli Rzav at the village of Donje Vardište. As one of the consequences of the ecological protests in various parts of Serbia since 2019, especially against the
small hydros, a survey was conducted in western and central Serbia to check the effects of such facilities regarding the nature. The survey of nine streams was conducted by the Faculty for Natural and Mathematical Sciences in
Kragujevac and local branch of the
World Wide Fund for Nature, the WWF-Adria. The Crni Rzav was described as an "example of the river which, under the pressure from small hydros, completely lost the diversity of its wildlife and visual identity". The river's natural course was changed and its role in reducing the effects of the climate change was diminished. Troubling changes of the habitats were recorded, as a result of drastic reduction of the water quantity and overgrowth of algae which specifically affected the aquatic
macroinvertebrate fauna. == Rzav ==