Drilled wells can be of varying depth. List of Glossary Terms dug well a large diameter well dug by hand, usually old and often cased by concrete or hand-laid bricks. Such wells typically reach less than 50 feet in depth and are easily and frequently contaminated. List of Glossary Terms effluent the discharge of a pollutant in a liquid form, often from a pipe into a stream or river. List of Glossary Terms erosion the wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep.
Geological erosion is natural occurring erosion over long periods of time.
Accelerated erosion is more rapid than normal erosion and results primarily from man's activities. Erosion is further classified by the amount and pattern of soil removal and transport as gully, interrill, rill, sheet, and splash or raindrop erosion. List of Glossary Terms eutrophication the natural or artificial process of nutrient enrichment whereby a water body becomes filled with aquatic plants and low oxygen content. The low oxygen level is detrimental to fish. In water, the major sources of nitrates are septic tanks, feed lots and fertilizers.