New USGS Groundwater Report on the Occurrence of Trace Elements in Radon

A new USGS study evaluates the occurrence of 23 trace elements and radon in groundwater samples from over 5,000 wells collected nationwide from 1992-2003. This study is part of the USGS National Water-Quality Assessment (NAWQA) Program, which has assessed the physical, chemical, and biological characteristics of streams, rivers, and groundwater across the Nation since 1991. The report presents trace element occurrence, describes factors that influence the spatial distribution of trace elements, and compares concentrations to human-health benchmarks. Following are selected highlights from the report:

  • About 20% of untreated water samples from public, private, and monitoring wells contain concentrations of at least one trace element, such as arsenic, manganese and uranium, at levels of potential health concern.
  • Differences in the concentration of trace elements are related to the climatic conditions and land use of the area.
  • Basic geology and geochemistry of water samples helps to predict risk of trace elements exceeding human-health benchmarks.
  • About 10 percent of wells that had a trace element concentration in excess of human health benchmarks actually contained two or more trace elements exceeding human health benchmarks.

Go to: to view and/or download a copy of the full report and accompanying press release.  For more information about the USGS NAWQA program, visit