The water may look pure and majestic from the Rockies, but TomFromTheShade is right on the dot withthis one. I remember the parasites sectionof myBiology class in high school, it was enough to make you never want to go outside again. Injest a tapeworm, and you'll wish you never went on the hunting trip. There's been records of them growing up to 20 feet+ inside people's intestines. Then there's Trichinella, which you can get from eating undercooked pig and venison. The parasites move through your digestive system, into the blood system, and cyst in your muscles.They are treatable, but in rare cases, the infestation spreads throughout the body and becomes lethal. My teacher told us of a case where a guy died when the infection spread into his brain! Not a pretty picture.