February 12, 2010--How ground water contamination spreads (Environmental News Network)

Why are some wells contaminated and some are not? All wells are not equally vulnerable to contamination because of differences in three factors: the general aquifer chemistry, groundwater age, and paths within aquifer systems that allow water and contaminants to reach a well. More than 100 million people in the United States receive their drinking water from public groundwater systems, which can be vulnerable to naturally occurring contaminants such as radon, uranium, arsenic, and man made compounds, including fertilizers, septic tank leachate, solvents and gasoline hydrocarbons. The US Geological Service (USGS) has tracked in a recent study the movement of contaminants in groundwater and in public supply wells in. The importance of each factor differs among the various aquifer settings, depending upon natural geology and local aquifer conditions, as well as human activities related to land use and well construction and operation. “Our findings can help public supply well managers protect drinking water sources by prioritizing their monitoring programs and improving decisions related to land use planning, well modifications or changes in pumping scenarios that might help to reduce movement of contaminants to wells,” said Sandra Ebert