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A gasoline truck driver prepares to pump gasoline into an underground tank at an Arco service station in Mill Valley, Calif. - 

KAI RYSSDAL: In Washington today, underground fuel storage tanks. Like the ones at your corner gas station. They're leaking. A lot. That's a bad thing.

The Government Accountability Office says taxpayers are due to get a $12 billion bill for the clean-up. Our Washington bureau chief John Dimsdale has more.

JOHN DIMSDALE: It costs on average $125,000 to clean up one underground spill. And the GAO says the public's responsible for some 54,000 leaky tanks.

Mopping up the spills is a state responsibility. Washington helps out with a federal trust fund that collects a tenth of a cent per gallon tax on gasoline. There's $2.5 billion in the trust fund — and it's growing.

But the Environmental Protection Agency's proposal for tank clean-up next year would be less than the interest the trust fund will earn. Some members of Congress and environmental groups think it's time to dip more deeply into the reserve.

Ed Hopkins is with the Sierra Club.

ED HOPKINS: It just makes the numbers in the budget look a little better. What they should really be doing with this money is spending it to solve a lot of the problems that communities have with underground storage tanks leaking.

The director of the EPA's Office of Underground Storage Tanks, Cliff Rothenstein, confirms there are spending constraints on his agency.

CLIFF ROTHENSTEIN: It counts against the bottom line of our budget, which means if there's an increase in one program, there's a decrease in another program because we're subject to an overall budget.

While Rothenstein says the EPA and states are making progress with regular inspections and requiring better equipment, GAO recommends the government do a better job of making sure tank owners have enough insurance to cover clean-up costs without sticking taxpayers with the bill.

In Washington, I'm John Dimsdale for Marketplace.