When I was into gold prospectig more and made it up to some of those areas, I had heard that if you found a corregated drain pipe that was from the dirt roads and collection points around these areas (not really sewage pipes, but road ones), that you could dig out the dirt in the bottom of each riffle and pan it to find gold. These pipes act just like a natural sluice. Try that one out and let me know if it works! I tried it when I found a pipe, but the angle on the pipe might have been to great to trap much. 8)