CHLORIDE IN DOMESTIC WELLS AND PROXIMITY TO ROADWAYS IN VERMONT

There is growing evidence that road salt, in the form of sodium chloride, is affecting groundwater across New England. Recent studies suggest that chloride concentrations are increasing in groundwater. These increases can affect glacial and fractured bedrock aquifers across the region, primarily in urbanized areas or along major roadways.

In Vermont, 30 percent of the residents obtain their drinking water from private wells and springs. However, no statewide analysis of the spatial and temporal distribution of chloride concentrations in groundwater has been done. The Vermont State Department of Health (VDH) maintains a database of groundwater quality and well location that can be analyzed to determine the extent of chloride contamination in the groundwater across the State, and the rate of chloride concentrations exceeding the United States Environmental Protection Agency (EPA) Secondary Maximum Contaminate Level (SMCL) of 250 mg/L.

The U.S. Geological Survey, in cooperation with VDH, is starting a project that will examine the occurrence and factors related to elevated concentrations of chloride in wells located near roadways in the State of Vermont with the goal of enhancing the understanding of chloride prevalence in the State. Because chloride can increase the corrosivity of water and affect water supply lead concentrations, findings from this study may be particularly important to private well owners.

Findings from this study would also allow the State to do targeted well testing outreach, particularly in communities with a high percentage of wells over the EPA SMCL. The findings will aid the State in creating general drinking water testing recommendations for unregulated drinking water and provide documentation for or against concerns from the public about road salt contamination.