The McMoanin Hydraulic Mine is hidden deep in the National Forest. I found it on 1897 Sierra County Folio Map, but that's the only reference to it I could find. 

  The cabins here have been used and maintained on and off over the years, perhaps by hunters. A tin roof was added to one of the cabins, from what we found inside, it looks like these cabins have not been used for about 10 years.