Hazardous substances that leak from underground storage tanks can contaminate the soil and water and pose continuing health risks. Leaks of methyl tertiary butyl ether--a fuel additive--have forced several communities to close their wells. GAO surveyed all 50 states and the District of Columbia to determine whether tanks are compliant with the Environmental Protection Agency's (EPA) underground storage tank (UST) requirements. About 1.5 million tanks have been closed since the program was created, leaving about 693,000 tanks subject to UST requirements. Eighty-nine percent of these tanks had the required protective equipment installed, but nearly 30 percent of them were not properly operated and maintained. EPA estimates that the rest were inactive and empty. More than half of the states do not meet the minimum rate recommended by EPA for inspections. State officials said that they lacked the money, staff, and authority to conduct more inspections or more strongly enforce tank compliance. States reported that even tanks with the required leak prevention and detection equipment continue to leak, although the full extent of the problem is unknown. EPA is seeking better data on leaks from upgraded tanks and is considering whether it needs to set new tank requirements, such as double-walled tanks, to prevent future leaks.
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