TAMPA, FL - Nearly 4,700 fuel storage tanks operated by gas stations, governments, and businesses in Florida must be upgraded by the end of March or face shutdown, according to the St. Petersburg Times.

To protect drinking water, the state of Florida required owners to upgrade the tanks from single-wall protection to double walls - or permanently close them out. The deadline was Jan. 1. However, nearly 600 Tampa Bay area tanks still need upgrades at almost 200 locations, most of them fuel stations, according to a database by the Florida Department of Environmental Protection (DEP), reported the Times.

Now the state agency will give owners until March to upgrade or close off the tanks - or face fines starting in April.

Most of Florida's drinking water comes from groundwater that could be harmed by a leaking tank. The requirements are supposed to keep taxpayers from having to pay the cleanup costs after leaks taint soil and water.

The state won't fine owners if they have contracts for upgrades that will be done by March 31, or if they agree to consent orders if they need more time.

Upgrades can run up to $300,000, said Pat Moricca, president of the gas retailers group, which is a costly fee during recession, he said.

The Times said the DEP also created a list of preapproved contractors to speed the work.

Former Gov. Martinez said he couldn't explain why the deadline passed with so many tanks failing the state standard, according to the Times.