The Wilton Health Department is nearly finished with a database of all well contamination reports and water quality narratives to provide an overview of problematic areas in town, as far as well water is concerned.
Well water is an issue because many homes in town get water from private wells. Contaminants discovered in wells by the health department in the past couple of years, in cooperation with the state Department of Public Health, include uranium and arsenic.
“We have substantial data so far; we are just continuing the process,” said Barry Bogle, the town’s health director, speaking about the database under construction.
Wilton’s well contamination issues have been known for some time. They came to the public eye again in the past week when the U.S. Geological Survey issued a separate report reiterating what had already been known about the well water in Wilton.
Wells in Stamford and Weston also exceed the safety threshold set by the federal Environmental Protection Agency for arsenic and uranium, according to published reports.
The local health department tested 80 wells in the spring of 2015.
Both arsenic and uranium are considered toxic and can have a variety of adverse health effects if people are exposed at high enough levels and for a long period of time.
The EPA drinking water standard or action level for arsenic is 10 parts per billion. Of the 80 wells tested, arsenic was detected in seven samples, and two wells exceeded the action level.
Arsenic has no smell or taste and is classified as a human cancer-causing agent. Arsenic has been associated with increased risk of lung, bladder and skin cancers.
Thirty-three of the 80 wells had some level of uranium in them. The action level for uranium in drinking water is 30 parts per billion. Six of the 80 wells exceeded the uranium action level, but nine out of 10 had uranium levels below the action level.
Uranium is naturally present in bedrock, so deep bedrock wells are susceptible to contamination and shallow wells are less susceptible.
For wells that have unacceptable levels of arsenic, it can be removed with a special filtration system. Carbon filters can be effective.