Summary: The U.S. Army Corps of Engineers estimates that it will spend as much as $20 billion to clean up contamination at thousands of properties that were once owned, leased, or operated by the Defense Department (DOD). These properties contain hazardous, toxic, and radioactive wastes in the soil and water or in containers, such as underground storage tanks. The Corps is responsible for cleaning up the hazards, including removing underground storage tanks. DOD's annual report on its environmental restoration activities can provide a misleading picture of the Corps' accomplishments. DOD's accounts of completed projects include projects that were ineligible or that did not involve any actual cleanup effort. As a result, the impression is that--after 15 years and expenditures of $2.6 billion--more than half of the projects at formerly used defense sites have been completed. In reality, only about 32 percent of those projects that required actual cleanup actions have been completed, and those are the cheapest and least technologically challenging. The Corps estimates that the remaining projects will cost more than $13 billion and take upwards of 70 years to complete. The Corps' reporting of completed projects reflects DOD's reporting policies for all of its environmental cleanup programs, including those at closing bases and active installations. As such, progress on those cleanup programs may not be accurately pictured either. In addition, DOD's range survey did not include all formerly used defense sites properties that may contain unexploded ordnance and could be former training ranges. Consequently, DOD's inventory of training ranges is likely incomplete, and its estimated cost to clean up these ranges is likely understated.