Levels of contaminants found in more than two dozen water wells in Dimock Township, Susquehanna County, in 2012 were high enough to affect residents’ health, create a physical hazard or otherwise “make the water unsuitable for drinking” in its raw state, a federal health agency reported Tuesday.
The Agency for Toxic Substances and Disease Registry released the report after reviewing water sampling data collected four years ago by the U.S. Environmental Protection Agency during a high-profile investigation into groundwater contamination in the northeastern Pennsylvania community that was a focus of early Marcellus Shale development.
The health agency did not define the source of the contamination and it evaluated the wells for chemicals whether they occur naturally, are man-made or are influenced by human activities.
The analysis comes long after the EPA ended its investigation in Dimock, which is in the northeast corner of the state, by concluding that it did not need to take any further action after it found that water in all but five of the 64 wells it sampled was safe to drink and the others could be treated to safe levels.
The new report is likely to stir up concerns in a section of the community where state environmental regulators have, since April 2010, forbidden Texas-based Cabot Oil and Gas Corp. from drilling new gas wells until the water quality returns to pre-drilling conditions in 18 wells that the Pennsylvania Department of Environmental Protection says were contaminated by methane and metals related to Cabot’s gas wells.
Cabot says any contamination in area water wells occurs naturally or is unrelated to its operations.
The agency‘s report analyzed the same sampling data that EPA collected and evaluated in 2012, after residents approached the federal agencies with persistent concerns about the safety of their drinking water. The new analysis is conservative, the health agency said, and it assumes that residents are ingesting the maximum detected concentration of the chemicals found in the well water.
In 27 water wells, the agency found that levels of arsenic, cadmium, copper, iron, lead, lithium, manganese, potassium or sodium were high enough to affect the health of adults, children or people with existing health problems. A man-made chemical, 4-chlorophenyl-phenyl ether, was also detected in two water wells, but the agency said there is not enough information on its toxicology to determine if it can cause adverse health effects.
In 17 water wells, the agency found that methane levels could create a hazard if the flammable gas builds up in poorly ventilated areas. Three of five wells with high enough methane concentrations to pose an immediate safety hazard did not have methane treatment systems in place as of January 2013, the agency reported.
Conditions in Dimock have changed since 2012, the Agency for Toxic Substances and Disease Registry said in a handout to residents, including that some hydraulic fracturing activities, or well completions, were allowed to resume in the area after the federal investigation ended.
The state Department of Environmental Protection has concluded that gas drilling operations were responsible for high methane levels in three additional water supplies in Dimock since 2012, including one that had been under evaluation since 2009.
“Residents have raised new concerns about changes in drinking water quality since gas well completions have resumed,” the agency said in the handout.
“The levels of current exposures among Dimock residents to chemicals in their well water is uncertain. We do not have the information to clearly say whether a resident is drinking treated or untreated groundwater, or whether water treatment was successful or remains effective.”
In a statement, Cabot said the data reviewed by the Agency for Toxic Substances and Disease Registry “does not indicate that those contaminants detected have any relationship to oil and gas development in Dimock.”
“The existence of preexisting, naturally occurring methane in the area prior to any natural gas activity has been confirmed by numerous agencies and testimony by life-long residents. And within the study itself, the ATSDR clearly states the data was included ‘regardless of the source of the contaminant in the residential well.’”
Contamination is common in Pennsylvania’s largely unregulated 1 million private water wells. Studies by Penn State have found 40 percent of private water wells in Pennsylvania fail to meet at least one health-based drinking-water standard, most often because of bacterial contamination.
The Agency for Toxic Substances and Disease Registry recommended that regulatory agencies either conduct or supervise additional well water sampling in the Dimock area.
Cabot has continued to test water supplies it has access to in the 9-square-mile moratorium area under a consent order with the state. DEP has conducted additional sampling of its own in the region, DEP spokesman Neil Shader said, and it will share those results with the Agency for Toxic Substances and Disease Registry.
Some Dimock residents said the new report leaves them with more unanswered questions.
Victoria Switzer said her household stopped drinking any water from the tap in 2009, “so part of me feels relieved that I didn’t just say, ‘Oh well, we’ll drink the water.’”
“I have concern for people who have been drinking the water but shouldn’t be,” she added. “But my main concern is, now what?”
Laura Legere: email@example.com.