Bacteria Levels in Wilderness Water Tested

[An Analysis of Wilderness Water in Kings Canyon, Sequoia, and Yosemite National Parks for Coliform and Pathologic Bacteria. WEM. 2004; 15 (4): 39-45]

Newswise — The safety and quality of backcountry water in Kings Canyon, Sequoia, and Yosemite National Parks in California was put to the test in a study by Robert W. Derlet, UC Davis Medical School. The study, published in the December issue of Wilderness & Environmental Medicine, found that of the 55 wilderness lakes and streams sampled, they all contained expected and normal levels of aquatic bacteria. Backpackers, hikers, fishermen and others who use national parks for recreational purposes rely on wilderness water from lakes and streams. The safety of backcountry water is imperative to the health of the parks' recreational users.

The researchers' goal was to determine the presence of pathogenic, or disease causing, bacteria, and coliform, relating to E coli. Water samples were collected from June through September, 2003. Of the 55 sites sampled at the three national parks, coliform was absent in 33. These sites are lightly used by backpackers but not used by domestic animals.

Varying levels of coliform bacteria was detected in 22 of the sites that are located below areas that backpackers or park animals use. The coliform bacteria found at these 22 sites were identified as E coli. At nine of those 22 sites, higher levels of coliform were found and at 13 of the sites, lower levels were found.

The study determined that most of the backcountry lakes and streams in the three national parks do not contain coliform or pathogenic organisms. Researchers believe the low levels of coliform found at 13 of the 22 positive locations are a result of human contamination, pack animals, or part of the natural environment at that location. All of the sites tested contained normal levels of aquatic bacteria that, if not present, would jeopardize the ecologic balance and food chain, from frogs to fish.

Wilderness & Environmental Medicine is a peer-reviewed quarterly medical journal published by the Wilderness Medical Society. For more information, visit http://www.wms.org

To view the article, visit: http://www.allenpress.com/pdf/weme_15_409_238_244.pdf