You reminded me to go find my small waterproof case for my cellphone. My ring is 3 vibrations and then crickets. There was a guy enjoying the cool water yesterday on his inflatable yak with he I-pod blaring and yakking on his phone at the ramp. It was not a pristine wilderness setting but somewhat annoying anyway. I have used my cell phone to help out rental yak users a few times when they had trouble with their craft and needed to be picked up mid trip.

The question that came to my mind about the upstream-downstream thing was "Won't you both be fishing each others used water?"