The U.S. Geological Survey study found that 15 percent of groundwater samples from 66 household wells across south-central New York contained naturally occurring methane at levels high enough to warrant monitoring or remediation, even though none of the water wells was within a mile of existing or abandoned natural gas wells. Methane is an odorless, colorless gas which can be explosive in high concentration.
USGS scientist Paul Heisig said the levels in four of the wells were so high that water coming out of a tap could potentially be lit with a match, or be an explosive risk.
Heisig added that the study found significant differences between water wells located in valleys and upland areas: nearly 30 percent of groundwater samples from valleys tested at or above levels that suggest cause for concern, but none of the samples from upland wells did.
Heisig said the research should help policy makers and the public understand the conditions in the region. The testing was done in the summer of 2012 and the study area included about 1,800 square miles in parts of Broome, Tioga, Chemung, Chenango, and Delaware counties that have Marcellus Shale gas resources that the industry wants to drill.
New York has had a moratorium since 2008 on the "fracking" drilling method that's used to tap shale gas deposits.
Heisig said his team didn't specifically try to link the gas in water wells to the Marcellus formation, but rather focused on documenting the naturally occurring variations in water wells in the region.
In a nearby region of northeastern Pennsylvania, Duke University scientists found that some water wells located within a mile of new gas drilling wells had higher levels of methane, compared to those farther away. State officials, meanwhile, found that some methane contamination in the area of Dimock, subject of the anti-fracking documentary "Gasland," was caused by nearby drilling.