The U.S. Environmental Protection Agency projects include three sites in California, four in Colorado, two in Montana and one in Missouri.
A stop-work order affecting the sites was issued last month but officials did not disclose specifics. Details were provided following repeated requests from The Associated Press.
EPA Assistant Administrator Mathy Stanislaus says the suspended sites have the potential for contaminated water to build up inside mine workings.
That would set the stage for a blowout such as in Colorado, where an EPA team triggered a 3-million-gallon release of toxic sludge while doing excavation work on a mine near Silverton. The AP also recently obtained this video from shortly after the spill happened in August.
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