Testing of Private Water Wells in Eastern Massachusetts Indicates High Levels of Arsenic
With many groundwater contaminants, research on health impact is often ongoing. Long-term health effects can be difficult to confirm in terms of levels of contaminants present and ingestion rates. There are often mitigating circumstances that make determining an accurate safe level difficult. As more information becomes known through study, the Environmental Protection Agency can then set drinking water standards for these contaminants.
Due to an improved understanding of the impacts of arsenic and uranium on human health, the EPA has recently established standards for both of these naturally occurring elements. It falls upon homeowners with private wells to test their water supply to determine if it exceeds the newly established safe level for arsenic and uranium.
Standards Can Change As More Becomes Known
In 2003 the EPA established a standard for uranium in public drinking water of 30 parts per billion (ppb). Back in 2001, the EPA dropped the standard for arsenic from 50 ppb to 10 ppb. This new standard became active in 2006.
In 2008 the U.S. Geological Survey along with the Massachusetts Department of Public Health undertook a study to detect the presence of naturally occurring arsenic and uranium in private bedrock water supply wells in east central and northeaster Massachusetts.
This area of the country was selected because existing public well records showed it to have a high level of arsenic concentrations. The study included uranium because less is understood about the distribution of this contaminant and researchers wanted to gain a better understanding of its relationship with the bedrock geology of Massachusetts.
The USGS study investigated samples from 478 wells in 116 communities in this area. Samples were distributed among various bedrock formations throughout the study area. The study found a correlation between the bedrock geology and arsenic and uranium concentrations present. However, the study found a strong correlation between contaminant levels and the proximity of the well to the Clinton / Newbury fault zone, that was not dependent on bedrock. The study found a higher probability arsenic zone that extended to the west of the fault zone. The Clinton / Newbury fault zone extends from the Merrimack River Valley in the northeast to the eastern end of the Massachusetts and Connecticut border in the south. This Arsenic contamination probability zone is visible in this illustration.
The USGS used the results of their testing sample to predict the number of wells in the study area that were expected to exceed the arsenic standard by multiplying the probabilities by the number of wells in the area. This included the zone west of the fault line as well as the probability statistics for individual bedrock geology for areas outside the probability zone.
The predicted number of wells exceeding the standard for uranium were calculated in a similar manner.
Based upon the results of the study, the USGS predicts:
• Approximately 5,700 wells, out of 90,000 may have arsenic levels that exceed the standards for arsenic, of which 3,800 may be being used without treatment for arsenic removal.
• Approximately 3,300 bedrock wells out of 90,000 may have uranium levels that exceed standards and approximately 3000 of these are being used without treatment for uranium removal.
What To Do If You Live Within The High Arsenic Probability Zone
The first step is determining if arsenic and uranium are present, and at what levels. If you live within this high probability zone you should have your well tested for arsenic and radionuclides including uranium.
If the results of initial testing show levels that exceed the EPA standard of 10ppb for arsenic and 30ppb for uranium you should speak with your well water professional about water treatment systems that can remove these substances from your water supply.
Arsenic and uranium may be present in your well due to these substances being present in the soil and bedrock geology. This study found a high correlation between the various different bedrock formations of this region and the levels of contaminants present. If you live in an area of Massachusetts as outlined in the above illustration, have your water tested as soon as possible. The probability that your well poses a health concern is somewhat low. The actual health risks depend on the level of contaminant, the amount consumed, and the number of years of consumption.
If you live in one of these affected cities or towns, contact your local well water professional and arrange to have your well tested. If you're not sure where to go, give the experts at Skillings & Sons a call. We're always happy to help homeowners and answer any questions you might have about the health of your water well