The USGS and the Massachusetts Department of Environmental Protection are conducting a study of private wells in selected Massachusetts counties. The goal of the study is to assess:

• The number of private wells with arsenic or uranium concentrations that are greater than the current drinking water standards.
• The degree to which bedrock units correlate with concentrations of uranium and arsenic.

This study about arsenic and uranium was prompted by recent changes in federal drinking water standards and the results of previous studies. In 2000, the standard for safe drinking water for uranium was established at 0.03 milligrams per liter (mg/L). In 2006, the standard for arsenic was lowered from 0.05 mg/L to 0.01 mg/L. Although bedrock is thought to be a source for arsenic and uranium, the association between these elements and bedrock type has not been established for Massachusetts. The focus of this investigation is east-central Massachusetts, where elevated levels of arsenic have previously been detected in public wells. 

Public wells are relatively uncommon in bedrock because of low water yield; however, private bedrock wells are very common and results could substantially increase knowledge about arsenic and uranium distribution.

Residents with private wells in the Massachusetts’ counties Essex, Middlesex, and Worcester are needed for this study. In early March, some 1,600 residents will receive letters asking them to help scientists determine if arsenic or uranium concentrations are elevated in their well water.

The letters will come from the U.S. Geological Survey, and instructions and sampling kits will be provided; there is no cost to participate. Following the study, well owners will receive confidential results of the tests.