An estimated 12 million holes have been drilled in the past 150 years by companies looking for oil and gas, and although many were plugged when they ran dry hundreds of thousands have been simply abandoned and forgotten with no record of their existence or location, ProPublica reported Monday.
The abandoned wells can allow oil, gas or brine-laden water to contaminate groundwater supplies or reach the surface, government reports have warned.
The drinking water source for Fort Knox, Ky., has been polluted by abandoned wells, and oil has been detected leaking into water wells in Ohio and Michigan.
Texas, New York, Colorado and other states where drilling has taken place are experiencing similar situations, ProPublica reported.
A survey published in 2008 by the Interstate Oil and Gas Compact Commission, a multi-state agency of regulators and industry representatives, said states had discovered almost 60,000 wells that need to be plugged and estimated there may be as many as a million more.