Waterfall on the slopes of Quebrada Cayesh: good clean drinking water!

There were several of these big waterfalls. I was told not to take water from the main stream down in the center of the valley, but use the side streams instead. There were several of those, so it was no trouble finding one. I don't know why I shouldn't use the water in the main stream. There were a some cows around, but that's common in the valleys of the Cordillera Blanca, so it must have been something else. Other climbers I talked to didn't know about the water and did take it from the main river. They said it didn't taste nice. So, if it's not just polluted by animals, the only thing that I can think of is that there might be some metal deposits leaking into the water. Perhaps there is an old mine up there? Or is it something natural? 17 June 2011.