Today I spoke with somebody who got giardia from the Round Valley faucet. (He did not eat at the old restaurant.
) The last time the state park cleaned out the tank there were rats in there, so that makes sense that even though it's an "underground source" there is giardia which is normally present in above-ground sources. A lot of people, including myself, have taken that water straight without purifying, but apparently they put that warning sign there for good reason.