Nov. 10: This story has been corrected.

In its Sunday, Nov. 6, business feature, The New York Times wrote about concerns some residents across the country have about pollution in their water supplies from natural gas drilling. The paper traveled to northeastern Pennsylvania, where more than a dozen residents' water has been fouled by the drilling process and the state is arranging to replace their drinking-water supply.

ProPublica has been reporting on the water concerns there, in the town of Dimock, since late 2008.

At the end of its article, the Times used a quote that raised questions about whether gas drilling is responsible for the contamination, or whether the problem has been made up or overhyped.

The quote came from Martha Locey, a 78-year-old resident of the nearby town of Montrose, Pa., who said she's had methane in the water of her family farm for decades -- long before the drilling started.

"My father dug our well in 1945, and we knew it had lots of iron in it, and we thought it had something else, but we weren't sure, because it had lots of bubbles in it," Mrs. Locey said. "So my nephew took it to school in the '60s, and the science teacher lit it, and it burned, so he said, 'It's methane.'"

Mrs. Locey may be right. It's quite likely that her nephew did in fact light his water on fire almost 50 years ago -- and that the water contained gas. It just wasn't the same type of gas that is causing problems in Dimock.

Methane does occur naturally in water wells, and it is not uncommon in Pennsylvania water. But state officials long ago determined that the methane bubbling up in Dimock's wells was the result of the disruptive drilling processes taking place adjacent to the wells. The gas that typically is found naturally in water wells comes either from methane deposits somewhere near the earth's surface, or from the decomposition of bacteria (this is called biogenic methane).

Scientists have tested the molecular composition of the methane found in Dimock and determined that it came from the Devonian layer of shale, thousands of feet below the surface. In geologic geek-speak, it's called "thermogenic," meaning it is essentially the same kind of gas that the energy companies are drilling for.

Residents in Dimock and across the country have found thermogenic gas in their water where drilling is taking place. Many people are blaming the invasive and controversial drilling process called hydraulic fracturing, and federal authorities are studying whether that process in particular is endangering water supplies in several states. But whether it was fracking or some other part of the drilling process -- the construction of the wells, for example -- there is little debate among regulators and scientists that the contamination in Dimock is related to the drilling.

Inform our investigations: Do you have information or expertise relevant to this story? Help us and journalists around the country by sharing your stories and experiences.