(From ProPublica, which originally posted this piece, which was co-published with Politico, on Dec. 27, 2009.)

For more than a decade the energy industry has steadfastly argued before courts, Congress and the public that the federal law protecting drinking water should not be applied to hydraulic fracturing [2], the industrial process that is essential to extracting the nation’s vast natural gas reserves. In 2005 Congress, persuaded, passed a law prohibiting such regulation.

Now an important part of that argument — that most of the millions of gallons of toxic chemicals that drillers inject underground are removed for safe disposal, and are not permanently discarded inside the earth — does not apply to drilling in many of the nation’s booming new gas fields.

Three company spokesmen and a regulatory official said in separate interviews with ProPublica that as much as 85 percent of the fluids used during hydraulic fracturing is being left underground after wells are drilled in the Marcellus Shale, the massive gas deposit that stretches from New York to Tennessee.

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