You won't get much of an argument from me here. It's true that there's no certainty that backpackers, with the help of livestock, spread giardia to back-country waters. Afterall, it is callled, 'beaver fever.' None the less, giardia did spread in this country and it did spread to formerly clean back-country watersheds. Again, what happened in Missoula is an example. An amusing (or not so amusing) after effect of the Missoula contamination is that the particular watershed is still used but dogs are prohibited from certain areas of it.

Giardia has a way or reintroducing itself...many animals (people too?) are carriers without symptoms and giardia infestation from them can end up in previously clean waters. And every once in awhile, giardia shows up in a municipal water system...that's after the (not-so-effective) treatment. That's why UV treatment is being added to treatment systems that don't already have them. Similarly, I think some recent studies of waters in the Sierra Nevada found no giardia. But there's no assurance those waters will stay that way.

My own belief is that back country waters are pretty safe but that the story about dirty backpackers is probably true, too. So I treat or filter. I've watched an associate suffer through diagnosed giardia...the safeguards are no inconvenience or cost at all in comparison. If you're saying that the dirty-water threat is overblown, I agree, but...

I also wear my seat belt when I'm the only one on the road. S**t happens...sometimes in the water. <img src="/forums/images/graemlins/ooo.gif" alt="" />

FB