PORTLAND — The U.S. Geological Survey says it has mapped potentially harmful levels of arsenic in drinking water in more Maine locations than previously suspected.

Robert M. Lent of the USGS Maine Water Science Center in Augusta says the arsenic levels in the latest study “are some of the highest we have seen in private wells.”

Download and read the report.

Martha Nielsen, a USGS scientist, says new maps show areas with elevated arsenic levels. She says the maps can be used as a guide but she notes that arsenic levels can differ from well to well. She says that’s why it’s important to have private wells tested.

Download a map 0f Maine of wells with concentrations over 10 micrograms and a map with maximum concentrations of arsenic.

Nearly half of Mainers get drinking water from wells. But Andrew Smith with the Maine Center for Disease Control says only 40 percent of wells are tested.