Sorry, you're both wrong about the source of fluoride on Mt. San Jacinto. The DWA has told me directly that the only possible source of fluoride, along with any other pollutants, comes solely from evil hikers who are determined to foul their water source. Otherwise, I would think you were right.
BTW, I have long felt that it might be chancy to use those strong fluoride mouthwashes that are supposed to harden the enamel on your teeth. I wonder how they fit into this picture?
Incidentally, I find it difficult to type "fluoride" - my brain wants to type "flouride" since it would fit with the pattern like "four" and "pour". Sort of like trying to spell "pharaoh". Even the person who named the triple crown winner was unable to spell that word correctly. Sorry for the digression!