BACKCOUNTRY WATER QUALITY TESTS ARE
GOOD NEWS FOR CAMPERS
Sierra Nevada waters usually free of troublesome
bacteria except in high use areas
January 6, 2005
(SACRAMENTO, Calif.)
— Data collected by experts
from the UC
Davis School of Medicine have revealed that except for some
heavily used areas, streams and lakes in the high country of the
Sierra Nevada are generally clean and fresh.
The good news for campers can be found in a pair
of studies published in the latest issue of the quarterly medical
journal Wilderness
and Environmental Medicine. UC Davis physician Robert Derlet
and pathology researcher James Carlson present data gathered from
nearly 100 locations throughout the Sierra Nevada during the summer
of 2003, including Yosemite, Sequoia and Kings Canyon national
parks. Their goal was to analyze wilderness water quality for
the presence of harmful bacteria such as E. coli, which is typically
an indicator of contamination from human or animal waste.
Running counter to popular belief, the two researchers
downplay the risk of picking up Giardia in backcountry drinking
water. In the Sierra Nevada, E. coli and other pathogenic bacteria
may pose a greater risk than Giardia for causing waterborne illnesses
in people.
“What’s impressive is that more than
half of our water sampling sites had no water quality problems
whatsoever,” said Derlet, a professor of emergency medicine
at the UC Davis School of Medicine and an avid backpacker with
30 years of experience hiking in California’s high Sierra.
“People still should use water filters or purification techniques
like boiling drinking water in the backcountry. But our findings
also are an indication of the outstanding job done by National
Park Service in its wilderness management.”
Derlet has spent the past five years on water quality
studies in the Sierra Nevada. From his recent sampling sites,
only 17 had levels high enough to be directly linked to recreational
use or the presence of livestock.
“For these two studies, we looked at nearly100
streams and lakes over the 400-mile long mountain range,”
observed Derlet, who has given presentations to wilderness rangers
about infectious diseases and backcountry medicine.“We’ve
also analyzed water at many more Sierra Nevada lakes and streams
this past summer with consistent results. It’s not surprising
that waterways below roads, popular trails and well-used cattle
grazing areas often show the presence of harmful bacteria. However,
it will probably take a number of years and some sustained funding
to pinpoint the exact causes.”
The UC Davis physician says his studies are only
a snapshot in time, and that all streams and lakes tested in wilderness
areas typically contain a certain amount of naturally occurring
aquatic bacteria. Low levels of coliform bacteria actually can
be part of the natural environment. If bacteria were not present
in the water, it would jeopardize the balance of the aquatic ecosystem,
including everything from frogs to fish.
Currently working with renowned Lake Tahoe expert
and UC Davis professor Charles Goldman, Derlet has several other
water quality findings in the Sierra that he also hopes to research:
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Lakes are typically ‘cleaner’
than creeks, possibly because the ultraviolet rays of sunlight
work better at killing off bacteria in calm waters of a lake
than in the tumbling flows of a stream;
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Algae growth in backcountry waterways appears
to be getting worse;
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Bacteria readings appear higher at the beginning
of spring runoff rather than later in the summer when water
levels are lower and water quality is thought to be poorer;
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Valley air pollution could be contributing to water quality
problems in the Sierra Nevada. |
To view or download the two studies,
click on the following highlighted text:
“An
Analysis of Wilderness Water in Kings Canyon, Sequoia, and Yosemite
National Parks for Coliform and Pathologic Bacteria”
and “Coliform
and Pathologic Bacteria in Sierra Nevada National Forest Wilderness
Areas Lakes and Streams.”
Readers also can get information about other issues in wilderness
medicine by visiting the Wilderness
Medical Society.
The studies were supported in part by a grant from the Wilderness
Medical Society, with assistance from the U.S.
National Park Service.
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