I returned and when I came back to the official end of the path, I saw that 10-20 metres downstream, there is another flow of water coming from the left. And maybe that is the famous source. That is, the big river comes out of the mountain, and the other stream of water is only a tributary. It was not that easily to tell through the trees. I could only see the rapids, but not where they come from. I will have to try again next time I'm in the area.