MT has it, too, lots of it. You just haven't drank from the right creek yet. Getting it when you're 5 miles back in the mountains is something you really won't want to do twice. It's not in every creek or spring but how do you tell whether its in THIS creek? You're playing intestinal roulette.
BS. You just have to be smart where you drink. Giardia is one of the most overblown fears out there. We're not drinking from low lying ag streams, we're drinking the finest water on the planet from mountain streams.