Arsenic in Groundwater

Arsenic in groundwater is a concern because it is a known carcinogen and can cause skin damage or problems with human circulatory systems. In light of these concerns, the U.S. Environmental Protection Agency (USEPA) established a maximum contaminant level (MCL) of 10 micrograms per liter (USEPA, 2013) for drinking water.   Arsenic is a naturally occurring element that is usually found in combination with other elements.  For example, one of the ways arsenic could be introduced naturally into Indiana groundwater is through arsenic-bearing minerals in soil, sediment, or rock that dissolve over time.  In some areas of the United States, arsenic in groundwater can be attributed to human activities such as the application of arsenic-bearing pesticides to fruit orchards or the usage of arsenic compounds as a wood preservative (Welch with others, 2000).

The InWMC Groundwater Focus Committee is compiling arsenic testing results for groundwater samples taken from several thousand sites throughout Indiana.  Previous studies found that arsenic concentrations in potable untreated groundwater can be extremely variable even on a local scale because of well type, well depth, aquifer type, geology, and other factors (Thomas, 2003).  Although the testing results from Indiana monitoring sites seem somewhat plentiful, there are still wide data gaps and the fact that arsenic concentrations above the MCL occur in various parts of the state warrants further monitoring.  The InWMC GW Focus Committee is partnering with other entities to provide additional testing results where possible.  A more complete database will help to better define groundwater conditions where high concentrations commonly occur.

Water-resource Professionals in Indiana Focusing on Arsenic in Indiana Groundwater

  • Jerry Unterreiner (Indiana Dept. of Natural Resources)
  • Jim Sullivan (Indiana Dept. of Environmental Management)
  • Randy Bayless (U.S. Geological Survey)
  • Tracy Branam (Indiana Geological and Water Survey)
  • Carolyn Dowling (Ball State University)

Additional Arsenic Information from the InWMC

InWMC Groundwater Focus Committee, Arsenic in groundwater fact sheet.
InWMC Groundwater Focus Committee, Arsenic in Indiana groundwater: residential wells.

Related Resources

Indiana Department of Environmental Management, 2013, Arsenic fact sheet, accessed July 23, 2013 at

National Groundwater Association, 2012, Household technologies available to remove arsenic found in well water , accessed July 23, 2013 at

Indiana Department of Environmental Management, Statewide groundwater monitoring network, 2013, accessed July 23, 2013 at

Thomas, M.A., 2003, Arsenic in Midwestern glacial deposits-occurrence and relation to selected hydrogeologic and geochemical factors: U.S. Geological Survey, Water-Resources Investigations Report 03-4228, 36 p., accessed July 23, 2013 at

U.S. Environmental Protection Agency, 2013, National primary drinking water regulations, accessed July 23, 2013 at

Welch, A.H., Westjohn, D.B., Helsel, D.R., and Wanty, R.B., 2000, Arsenic in ground water of the United States– occurrence and geochemistry: Ground Water v.38 no.4, p.589-604, accessed July 23, 2013 at