Interesting story in The Guardian about Pennsylvania's incredible number of abandoned, undocumented wells - roughly estimated to be 200,000 - and their impacts. Their state Department of Environmental Protection is working to find and track the wells, but it's a monumental task that is progressing slowly - only an estimated 5% have been logged so far.
"No one knows exactly how many abandoned oil and gas wells litter Pennsylvania or the US. The state’s Department of Environmental Protection estimates the number is close to 200,000. Some estimates are a little lower, some much higher. Across the country, the number could be more than a million. Most of the wells are relic of of a time when states didn’t bother to regulate much of what happened on private land, including oil and gas drilling, and when most Americans didn’t think twice about a seemingly esoteric issue like the environment." - The Guardian
Since 1984 new regulations in the state have required oil and gas companies to register and plug abandoned wells, but the legacy of prior drilling is a stark reminder of the importance of forward-looking environmental stewardship for today's O&G industry.