The decision whether to go ahead with seismic tests for oil and natural gas off the Southeast coast has been further delayed, without a deadline.

The federal Bureau of Energy Management has put off a final decision on granting leases that has been expected for months. The delay is open-ended, said Connie Gillette, bureau media relations manager, to give more time “to properly review the extensive public comments the bureau received on it and to ensure the latest relevant science informs the final decision.”

Public comments were taken in 2012. The decision originally was expected as early as fall 2012.

The proposed exploration and drilling is politically charged. It’s hotly controversial in the Lowcountry, across the region and nation. People are sharply divided. A “Drill, baby, drill!” sentiment, wanting any new source of fuels and the revenue to be gained, is countered by concern for the potential damage to the coast, its wildlife and multimillion-dollar annual tourism revenue.

In seismic tests, crews detonate compressed air guns dragged behind ships, creating a series of blasts to read the “echo” beneath the sea floor. The blasts can deafen or injure marine mammals, such as whales or dolphins, that navigate by sonar echoes, and are suspected of injuring other marine life.

The elephant in the room is the doubt about just how much oil or gas might be out there. It’s generally accepted that not a whole lot of oil lies off South Carolina. There are two types of natural gas fields, and the type thought to be offshore is far more difficult to drill for, according to Mitchell Colgan, College of Charleston geology professor, who formerly worked in exploration research for Shell Oil Co.

But oil companies don’t usually do the early surveys; geophysical exploration companies do. Then they sell the data they find.

The Obama administration in 2010 lifted a long-standing ban on East Coast drilling, and the Department of the Interior began an exhaustive federal process to decide on leases. The delays on those leases have galvanized Republicans. The House of Representatives passed a bill in July to open the near coast to both tests and drilling. U.S. Sen. Tim Scott in July discussed potential legislation to give companies the green light farther out in the ocean, saying any oil rigs would be far enough offshore to be out of view and minimize any potential damage.

Environmental advocates have worked hard to stop the leases.

“Why would we permit exploration activities that we know will negatively impact a variety marine animals when we haven’t even evaluated if oil and gas development is appropriate for the South Atlantic?” said Hamilton Davis, of the Coastal Conservation League.

Marty Morganello, president of the local Surfriders Foundation chapter, called the extended delay a small victory, citing a Department of the Interior study that suggested the blasts could injure as many as 130,000 marine mammals.

At least a half-dozen companies have already applied for permits to explore for oil and natural gas along all or part of the Southeast coast. All of them want to look off South Carolina.

To explore the area off South Carolina alone could cost a company some $4 million or more.

How much the state would share in leasing fees or other revenue is still undecided.

Reach Bo Petersen at 937-5744, @bopete on twitter or Bo Petersen Reporting on Facebook.