State and Stamford health officials are urging residents with private wells to get their water tested for pesticides and other possible contaminants.

A study of 628 private wells by the Stamford Health Department found that 195 had some amount of the pesticides Chlordane or Dieldrin. More than half of those 195 had concentrations that put residents who regularly drink the water at a greater risk for health problems, as defined by the U.S. Environmental Protection Agency.

Joseph Kuntz, a Stamford lab technician, said that when health officials first discovered some well contamination in 2009, they expected it to be localized and due to the nearby Scofield Town Dump. But testing had unexpected results.

“We saw things on the New Canaan border, things on the Greenwich border, things on the Darien border,” Kuntz said, explaining that contamination was everywhere and may well extend beyond Stamford and Fairfield County. “And it was like, OK, this is something anybody with a well anywhere needs to be concerned about.”

Chlordane and Dieldrin were used for termite and other insect extermination in homes and on farms for decades in Connecticut. They were banned in the 1980s, and the EPA now says that exposure to such chemicals over a lifetime, even at trace amounts, can increase the risk of health problems.

“You can’t see it, you can’t taste it and you can’t smell it,” said Bill Warzecha, an environmental analyst at Connecticut’s Department of Energy and Environmental Protection. “And so except if you test it, you’re not going to know that it’s in there.”

About 2.3 million people, or 15 percent of the population, in New England get their water from private wells, which are largely unregulated. According to DEEP, 700,000 of those residents live in Connecticut, which is about 20 percent of the population. Any requirements that individual states or cities have imposed usually apply only to newly built wells and don’t extend to testing for pesticides.

Warzecha said the test that is generally required — which looks at bacteriological, physical and chemical qualities of the water — costs $100 to $150. Adding pesticides and other compounds to the test can add a significant cost.

“As you add those parameters, it increases the price of the test, into the range of several hundred if not up to a thousand dollars, and people sometimes can’t afford that,” he said.

Stamford, where Kuntz estimates that 5,000 households have private wells, is unique in offering lower-cost testing. The city health department contracted with a local laboratory to bring down the cost of a $350 test to just $100. More than 1,700 people have signed up to get their wells tested, and last year the city passed an ordinance requiring 750 wells to be tested each year starting in 2012.

Broader concerns

On the heels of Stamford’s data comes a broader study that reaffirms long-held concerns about the quality of New England’s groundwater. The U.S. Geological Society announced new findings last week that much of the region’s wells have levels of arsenic and manganese that exceed federal safety standards.

Most of the nearly 5,000 wells USGS scientists looked at were public-supply wells. In 13 percent of sites, arsenic was present at levels above federal safety standards; manganese was found at unsafe levels in more than 7 percent of sites; and a third of sites had levels of radon that were higher than the EPA’s proposed standards.

Those chemicals, unlike pesticides, are considered to be naturally occurring in New England’s bedrock and soil. But the EPA warns that as the U.S. population consumes more and more water, groundwater — relied on now by about 42 million people in the United States — will become more important, and contamination may be more of a concern.

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