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Ground Water Links
Groundwater is one of the world's most important natural resources, yet most of us do little to protect it. The fact is, a great many of us rely on groundwater for drinking, domestic, agricultural and industrial uses. Our natural environment, such as streams, fish, and wildlife also depend on groundwater.
Water that occurs below the Earth's surface is called groundwater. You find it within the pores of sand and gravel or the cracks of fractured rock beneath the land. Groundwater exists in these openings in the subsurface environment like water exists within a sponge. Some of it can be removed from the ground and used for things like drinking, watering crops, and in the Columbia Basin, cleaning potatoes in factories before they are made into French fries.
Water enters the ground from many sources. This might include rainfall and melting snow, water from irrigated lawns and farm fields, leakage from rivers high in the mountains, or irrigation canals. If the water from these sources does not evaporate or get used up by plants it seeps into the ground and eventually fills the cracks in the rock or the spaces between the soil particles and becomes groundwater.
Gravity is the main force that makes groundwater move. Water that seeps into the ground at high elevations is pulled downward by gravity. Because of this, groundwater generally moves downhill toward rivers or lakes at the bottom of valleys. Sometimes, rain and snow that falls high on the hills and water put on crops to make them grow seeps into the ground and moves downhill to drain into Rivers. The water generally must move through the small spaces between rock particles and through small cracks in rocks, so it travels very slowly. It may take many years for rain that falls this year to become groundwater and then make its way into the Columbia River.
Groundwater provides 97% of the Earth's drinkable water. Farms, cities, and factories often rely on groundwater. Groundwater stays at the same temperature all year so it can be used to heat houses in winter and cool them in summer. In some areas, groundwater has become increasingly important as a source of heat for "heat pumps." In some parts of the world where little rain falls, groundwater is the only source of water. Without it no one could live in those places, and no plants would grow.
Because of water quality's importance to the health of humans and ecosystems, federal and state governments and water users have focused attention in recent years on cleaning up polluted groundwater. Groundwater has been polluted in urban and rural areas by such things as industrial and municipal wastes; leaking sewers and septic tanks; animal feedlots; and lawn and crop fertilizers, pesticides, and herbicides. Scientists study how groundwater is polluted, including how below-ground differences in chemical composition as well as biological and chemical reactions affect the pollution. They look for levels of materials such as chromium, lead, mercury and arsenic - harmful in certain amounts - and how the pollutants might move with water below ground. |
