For the first time, U.S. Geological Survey scientists have mapped groundwater vulnerability to contamination from orphaned oil and gas wells, revealing serious risks to aquifers in Appalachia, the Gulf Coast, and California.
Martha Pskowski reports for Inside Climate News.
In short:
- Orphan wells — abandoned oil and gas wells without active owners — can leak contaminants like hydrocarbons and brine into groundwater, especially in regions with older, unregulated wells.
- A new USGS study found that 54% of the nation’s 117,672 documented orphan wells sit within aquifers that provide 94% of the country’s groundwater use. Pennsylvania, the Gulf Coast, and California were identified as particularly vulnerable.
- Some wells in Pennsylvania, dating back over a century, have deteriorated wooden or metal casings, increasing failure risks and already linked to groundwater contamination incidents in several states.
Key quote:
“The threats are still there. Just as we discover more wells, we discover additional threats.”
— Nicholas Gianoutsos, USGS scientist
Why this matters:
Across the U.S., millions depend on groundwater for drinking, farming, and industry. As climate change drives more frequent droughts, this vital resource faces growing pressure. Orphaned oil and gas wells, often forgotten relics of past drilling booms, pose an invisible hazard beneath the landscape. Their aging infrastructure can corrode or collapse, creating direct pathways for pollutants to reach aquifers. Pennsylvania, where the nation’s first oil wells were drilled, faces some of the worst risks, with deteriorating wells scattered near homes and water supplies. The problem extends to the Gulf Coast’s wetland-adjacent wells and California’s heavily farmed Central Valley, compounding threats to water security.
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