Risk lurks in Sierra waters
Posted: Wed Apr 26, 2006 6:45 am
From the San Jose Mercury News
Posted on Wed, Apr. 26, 2006
Risk lurks in Sierra waters
STUDY SHOWS E. COLI LEVELS FROM CATTLE
By Paul Rogers
Mercury News
Bay Area hikers heading to the Sierra Nevada this summer should be extra careful about where they find their drinking water, particularly if cows are nearby.
That's the upshot of a new study that found cattle-grazing in national forests between Lake Tahoe and Mount Whitney is the leading source of E. coli contamination in Sierra streams and lakes.
In fact, nearly every stream and lake frequented by cattle or pack animals contained unsafe levels of E. coli -- a bacterium found in livestock waste that can produce severe stomach illness and even kidney failure in humans. Areas without livestock -- even those regularly visited by backpackers -- almost never had E. coli in streams and lakes, according to the research.
Primary source
``The impact is significant. Livestock, primarily cattle, pollute the environment,'' said Dr. Robert Derlet, a physician at the University of California-Davis and co-author of the study, published in the latest issue of Wilderness and Environmental Medicine.
``They are the main source of microbial pollution in the Sierra.''
Derlet's research is the first to definitively compare the effects of livestock, campers, pack animals and wildlife in causing Sierra water pollution. It is expected to increase calls for the U.S. Forest Service to curtail grazing and pack animals in Sierra wilderness areas.
Daniel Cobb, a veteran outdoorsman who teaches backpacking classes for the Sierra Club's Loma Prieta chapter, based in Palo Alto, said he is more than familiar with the health risk.
Two years ago, Cobb and a group of backpackers encountered cattle in a remote area of the Carson-Iceberg Wilderness, on national forest land between Lake Tahoe and Yosemite National Park.
``There were 20 or 30 cows in the forest,'' Cobb said. ``One of our hikers came down with a fairly serious intestinal problem. He swam in the river a couple of times. Our theory was maybe he had accidentally gulped more water than the rest of us.''
Cobb, 51, recommends backpackers use water filters or chemical tablets to purify all drinking water from lakes and streams.
Cattle and sheep have grazed Sierra meadows since the 1860s.
They are not allowed in national parks, such as Yosemite. But they are permitted in national forests, where ranchers pay $1.56 per cow per month to rent federally owned lands.
Ranchers hold about 450 permits to graze 60,000 cows and 36,000 sheep in California's national forests.
In the study, Derlet sampled 60 Sierra streams and lakes in the John Muir, Emigrant, Golden Trout and other wilderness areas, along with Yosemite and Sequoia-Kings Canyon national parks.
Backpackers OK
In 15 areas where backpackers regularly camp but no livestock are allowed, only one stream contained E. coli above the level considered safe by the World Health Organization. Similarly, only one of 15 areas with no backpackers or livestock was contaminated.
But 12 of 15 water bodies in areas frequented by pack animals, and all 15 where cattle graze, had unsafe levels.
Matt Mathes, a spokesman for the Forest Service in Vallejo, said two-thirds of all livestock on California's national forests are in the Sierra.
``It's always good to have additional scientific studies,'' Mathes said. ``This is something we are definitely going to follow up on.''
Mathes said Forest Service officials can try to keep cattle away from streams and lakes by locating water troughs and salt licks away from natural water bodies. In some instances they can fence areas off, but they rarely remove cattle altogether, as some environmentalists want.
Removing cattle is controversial among rural politicians, and Mathes says it could encourage urban sprawl by denying ranches in the Sierra foothills grazing land they need.
``Many of these ranches would go out of business and would become yet another housing subdivision,'' he said.
But environmentalists called the study a wake-up call for public health.
``Public land managers need to take this report seriously and really look at the numbers and kinds of animals they are allowing in the Sierra to protect the health of human visitors,'' said attorney Johanna Wald with the Natural Resources Defense Council in San Francisco.