The water soon disappears below the Rinka waterfall before resurfacing in the lower part of the valley. It rises to the surface due to the impermeable Werfen layers and then flows over dark sedimentary clays, which gives it its black colour. From there it flows along a regulated riverbed all the way to the end of the valley, where it merges with the Jezera stream, which flows from the Matkov kot valley and forms the beginning of the Savinja river. The area of the spring of the Črna stream is located in the lower part of the Logar Valley Trail and, with its water reflections and soft-underfoot path, it is one of the most serene and mystical parts of the landscape park. The spring has been declared a natural monument.
The Savinja river springs to the surface at the ?gable? of the valley below the Okrešelj cirque at an altitude of 1,280 meters and then makes its way towards the 90-metre Rinka waterfall. The spring is permanent and the water at the spring is clean, of good quality and potable.
According to legend, a few centuries ago there was a glacial lake in the Matkov kot valley. The water was held back by a natural dam, which allegedly collapsed and the lake drained from the valley. The stream that flows through the valley is still called Jezera (the word ‘jezero’ means ‘lake’ in the Slovenian language), which is a reminder of the valley's ancient past.