Correlations between arsenic in Maine groundwater and microbial populations as determined by fluorescence in situ hybridization.

Arsenic is known to cause serious health effects when consumed in drinking water. In the state of Maine, approximately half of the population relies on private groundwater wells for their drinking water. Of those wells, as many as 13% may contain arsenic levels above the current EPA maximum contaminant level of 10 microgl(-1).