Map of Arsenic concentrations in groundwater of the United States
The map graphic image at https://www.sciencebase.gov/catalog/file/get/63140561d34e36012efa2b7f?name=arsenic_map.png illustrates arsenic values, 
in micrograms per liter, for groundwater samples from about 31,000 wells and springs in 49 states compiled 
by the United States Geological Survey (USGS). The map graphic …