Hazardous Waste Cleanup: Numbers of Contaminated Federal Sites, Estimated Costs, and EPA’s Oversight Role, GAO-15-830T: Published: Sep 11, 2015. Publicly Released: Sep 11, 2015.

“he Departments of Agriculture (USDA), the Interior, Defense (DOD), and Energy (DOE) have identified thousands of contaminated and potentially contaminated sites on land they manage but do not have a complete inventory of sites, in particular, for abandoned mines. GAO reported in January 2015 that USDA had identified 1,491 contaminated sites and many potentially contaminated sites. However, USDA did not have a reliable, centralized site inventory or plans and procedures for completing one, in particular, for abandoned mines. For example, officials at USDA’s Forest Service estimated that there were from 27,000 to 39,000 abandoned mines on its lands—approximately 20 percent of which may pose some level of risk to human health or the environment. GAO also reported that Interior had an inventory of 4,722 sites with confirmed or likely contamination. However, Interior’s Bureau of Land Management had identified over 30,000 abandoned mines that were not yet assessed for contamination, and this inventory was not complete. DOD reported to Congress in June 2014 that it had 38,804 sites in its inventory of sites with contamination. DOE reported that it has 16 sites in 11 states with contamination.”