A study says in spite of the thousands of people who visit California's Sierra Nevadas every year, most of the water in the high country is clean.
Researchers at the University of California Davis School of Medicine tested almost 100 rivers and lakes in the Sierras, including many in Yosemite, Sequoia and Kings Canyon national parks. They found only 17 with levels of disease-causing bacteria high enough to suggest that humans or grazing cattle were the cause.
Problematic water was more likely to be found below roads, popular hiking trails or cattle pastures, said Robert Derlet, a professor of emergency medicine and avid hiker who has been visiting the Sierras for more than 30 years.
Derlet said hikers should still filter or boil water. But he said his findings show the National Park Service is doing an "outstanding job" of keeping streams and lakes pristine.
The data has been published in the quarterly journal Wilderness and Environmental Medicine.
© Copyright 2005 by United Press International
