Sierra waters show little pollution
Backcountry lakes and streams in the Sierra generally show little bacterial contamination, even in areas backpackers frequent, two studies published last month in the journal Wilderness and Environmental Medicine show.
Researchers tested water from about 80 sites at three national parks -- Yosemite, Sequoia and Kings Canyon -- and six Forest Service areas, including wild land as well as grazing and backpacking areas. Researchers detected coliform, or fecal, bacteria in about half the sites, and areas with lots of cattle or hikers showed above-normal levels. Bacteria was too low at most sites to cause a health problem.
Backpacker and UC Davis professor Robert Derlet says his research also shows:
* The risk of contracting waterborne protozoa such as giardia is “overemphasized.”
* Lake water typically has lower bacteria levels than stream water.
* Despite mostly clean water, Sierra hikers and campers should filter or purify the water they drink.
-- Ashley Powers
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