Why are Some Water Supply Wells More Vulnerable to Contamination?

The U.S. Geological Survey’s National Water–Quality Assessment (NAWQA) Program has
released new information from a 10 year study of factors affecting public-supply-well vulnerability to contamination. To read the abstract -Click here>>

The report (Circular 1385 – 120 pgs – 18.2 MB ) describes why it is important to understand the sources of recharge water for a well, the geochemical conditions encountered by water drawn into a well, the mixture of waters of different ages that simultaneously enter a well, and if direct pathways exists in an aquifer that allow water and contaminants to rapidly move toward a well.

The USGS tracked the movement of contaminants in public water supply wells in Modesto, CA, Woodbury, CT, near Tampa, FL, York, NE, near Carson City and Sparks, NV, Glassboro, NJ, Albuquerque, NM, Dayton, OH, San Antonio, TX, and Salt Lake City, UT.

More than 100 million people in the United States,  about 35 % of the population, receive their drinking water from public groundwater systems.  These public water groundwater wells can be vulnerable to naturally occurring contaminants such as radon, uranium and arsenic, as well as commonly used manmade compounds, including fertilizers, septic-tank leachate, solvents and gasoline hydrocarbons. Public-supply wells are vulnerable to contamination that starts with groundwater vulnerability to contamination. Even wells within a single aquifer, however, may vary in terms of their vulnerability to contaminants in the aquifer, because individual wells produce unique mixtures of the groundwater.

This USGS video podcast uses examples from four locations with very different aquifer-well combinations to illustrate why some public-supply wells are more vulnerable to contaminants in aquifers than others.

For more information on how the science behind public-supply well vulnerability to contamination can be used to protect drinking water sources, please refer to the accompanying USGS fact sheets below.

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