See update at the bottom of this post.
This Pittsburgh Post-Gazette story by Laura Legere is a must-read. It reports that Pennsylvania state records show that oil and gas operations have damaged water supplies 209 times since the end of 2007, affecting 77 communities.
The story notes that "the number of impacts is small relative to the number of new oil and gas wells drilled during the same time period – nearly 20,000, according to DEP records." That's an overall rate of about 1 percent.
The total obviously includes conventional oil and gas wells, in additional to unconventional ones. According to MarcellusGas.org, 8,478 unconventional wells have been drilled or are under development.
So, this overview begs some questions - other than an obvious one about why this information has never been made publicly available before.
How many of the 209 contamination cases were related to conventional gas development? Unconventional? Is one type more problematic than the other?
Is there any relation between the culprit wells and proximity to contaminated water supplies? And what does that say about current setback and water testing requirements?
Is any level of contamination "acceptable"? I doubt anyone living in those 77 affected communities would think so. And neither should regulators nor the industry.
To be sure, Pennsylvania needs to regulate private water wells. It's one of only two states that doesn't. But some forensic analysis of DEP's data is in order to answer these - and I'm sure other - questions.
August 29, 2014 update: The Wall Street Journal reports today that DEP has released some details - there are heavy redactions, from a quick eyeballing of some of the linked info - of what are now 243 cases of contamination. The info is posted here.