The alpine lakes of the Sierra Nevada are very sensitive to acidic deposition, since the soils derived from granitic bedrock cannot neutralize acids well. When Sequoia and Kings Canyon National Parks were established, boundaries were drawn to protect the parks' natural resources. The San Joaquin Valley is ideally shaped to trap pollutants in the atmosphere. Mountain ranges to the west, south and east form the sides of a large basin. Frequent inversions, warmer air on top of cooler air, create an atmospheric lid over the valley.
Coastal air enters the valley from the north and flows south, collecting pollutants along the way.
The Tehachapi Mountains, a barrier to southward flow, cause an eddy to form in the vicinity of Visalia and Fresno, adjacent to these parks. This circulating load of contaminants is carried into Sequoia and Kings Canyon National Parks by rising daytime air currents. During the past hundred years, we have replaced the marshes, grasslands and oak groves in the San Joaquin Valley with agriculture, cities and industries. While the potential health effects due to air pollution are alarming, other areas of our lives are also impacted. Since this is one of the fastest growing areas of California, pollution problems will continue to increase, unless we act now.