The states reported a variety of operational and maintenance problems, such as operators turning off leak detection equipment. However, only 19 states physically inspect all of their tanks at least once every 3 years—the minimum that EPA considers necessary for effective tank monitoring. The remaining 22 states do not inspect all tanks, but instead generally target inspections to potentially problematic tanks, such as those close to drinking water sources. Some Tanks Continue to Leak Even After They Have Been Upgraded, Although the Extent of this Problem is Unknown

In fiscal year 2000, EPA and the states confirmed a total of more than 14,500 leaks or releases from regulated tanks, although the Agency and many of the states could not verify whether the releases had occurred before or after the tanks had been upgraded. In closing, the states and EPA cannot ensure that all regulated tanks have the required equipment to prevent health risks from fuel leaks, spills, and overfills or that tanks are safely operated and maintained.
Why GAO Did This Study

Contaminated soil or water resulting from leaks at underground storage tanks can pose serious health risks. In 1984, Congress created the Underground Storage Tank (UST) program to protect the public from potential leaks. Under the program, the Environmental Protection Agency required tank owners to install new leak detection equipment and new spill-, overfill-, and corrosion-prevention equipment.

What GAO Found

GAO found that about 1.5 million tanks have been permanently closed since the program was created, but more than half of the states do not inspect all of their tanks often enough to meet the minimum rate recommended by EPA--at least once every three years. 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.