Sequoia and Kings Canyon National
Parks are downwind of one of the most productive
agricultural areas in the world, the San Joaquin
Valley. Every year, tons 
of pesticides are applied to these crops
-- over 45,000 tons in 1994 alone. Pesticides that
become volatilized -- suspended in the atmosphere as
particulates -- drift into the Parks on prevailing
winds. Consequently, organophosphates from fertilizer
are found in precipitation as high as 6,300 ft.
(1,920 meters) in Sequoia National Park. Other
synthetic chemicals, such as PCBs (polychlorinated
biphenyls) are also finding their way into the parks.
PCBs are found as in a variety of industrial and
consumer products such as cooling compounds,
electronics, paints, varnishes, plastics, inks and
pesticides. Some PCBs have negative effects on
animals by imitating specific hormones in
concentrations as small as parts per trillion. They
can cause changes in wildlife reproductive capacity,
longevity, intelligence, and behavior, or can lead to
cancer or mutations. They are inconspicuous, but
potentially dangerous.
 |
Application of
pesticides to citrus groves in the Central Valley of California.
© NPS photo.
|
While studies have not yet been
conducted to establish cause-and-effect links between
synthetic chemical drift into the parks and effects
on park ecosystems, circumstantial evidence suggests
that impacts to park wildlife may be occurring. For
example, the peregrine falcons that nest at Moro Rock
in Sequoia National Park have never been able to
produce offspring. Abandoned eggs contained high quantities
(13 mg/kg wet weight) of DDE (the breakdown product
of the US-banned pesticide DDT), and eggshells
averaged 15% thinner than they should be. More
recently, the peregrines produced eggs that lacked
the normal smooth waxy brown-spotted shell; instead
the shells were white and chalky. Additionally, the
foothill yellow-legged frog completely disappeared
from these parks in the 1970s, and today exists in
the Sierra Nevada only in a handful of widely
scattered populations along the western foothills.
The frog is much more common on the opposite side of
the San Joaquin Valley (in the foothills of the Coast
Range), upwind from pesticide drift. Synthetic
chemical drift may also be playing a role in the
ongoing decline in mountain yellow-legged frogs in
these parks, though other factors, such as non-native
fish introduction to park lakes, are also likely to
be important.
For more information, visit the California
Department of Pesticide Regulation
web site.
SEKI
Natural Resources Home Page
