Each of these places is described in more detail below. Ground water is the water below the surface within the earth that supplies wells and springs. Fifty percent of people in the United States and 95 percent of the rural population rely on this ground water for drinking water. Therefore, contamination of ground water is a national issue. For more information, click on Pesticides in Ground Water .
Surface water is the water that lies directly on the earth's surface, such as streams and lakes.
It provides 50 percent of the drinking water for the population, particularly in the urban areas. For more information, click on Pesticides in Surface Waters . The atmosphere is an important component of the hydrologic cycle because it replenishes both the surface and the ground water. For example, precipitation cleans and the atmosphere of pesticide vapors and particles by depositing them on the earth's surface. For more information, click on Pesticides in the Atmosphere .