Oil and gas plumes found at site of 13-year-old leak in Gulf

Federal regulators have found fresh evidence of an "ongoing oil release" at the site of a 13-year-old oil leak in the Gulf of Mexico, where chronic sheens often stretch for miles (kilometers) off Louisiana's coast, according to government lawyers.

In a court filing Friday, Justice Department attorneys said recent scientific surveys revealed two plumes of oil and gas flowing from where an underwater mudslide during Hurricane Ivan in 2004 toppled an offshore platform and buried the cluster of wells owned by Taylor Energy Corp.

The New Orleans-based company has repeatedly insisted there is no evidence that oil is seeping from any of its unplugged wells on the seafloor. The government's court filing doesn't address whether any of Taylor's wells could be the source of the plumes.

"There is no evidence of an actively leaking well, and all evidence continues to support the conclusion of remnant oil that has long been trapped in sediment on the sea floor," Taylor Energy spokesman Todd Ragusa said in a statement Monday.

But the presence of the plumes could complicate the company's efforts to negotiate a settlement that could allow it to recover millions of dollars it set aside for work to end the leak.

Taylor Energy sued the federal government nearly two years ago, seeking to recover up to $432 million from a trust it formed nearly a decade ago. The lawsuit has remained on hold for months amid settlement talks between the government and company.

Those negotiations were ongoing when the Interior Department's Bureau of Safety and Environmental Enforcement conducted an underwater survey of the leak site in September, using a remotely operated vehicle. Earlier this year, scientists for the government and the company also performed a series of studies at the leak site.

The survey and studies showed the two "active plumes" emanating from a depression adjacent to and partly underneath the wreckage of Taylor Energy's toppled platform, Justice Department lawyers said in Friday's filing. They didn't disclose any other details of their findings.

In its January 2016 lawsuit, the company said it had eliminated two oil plumes that were present at the site in Ivan's aftermath. Sonar surveys "confirmed an absence of any plumes (well leaks) remaining in existence," the company said in a November 2016 court filing.

Taylor Energy has argued nothing can be done to completely eliminate the persistent slicks on the surface. The company has claimed the sheens are coming from residual oil oozing from contaminated sediment.

Ragusa, Taylor Energy's spokesman, said the recent detection of plumes "is not new information" and "merely refers to a well-known water column anomaly largely consisting of naturally occurring biogenic gas, which is prevalent in the Mississippi River Delta area."

But an expert said the plumes could be the source of the oil on the water's surface.

"If these plumes are associated with the oil slicks on the surface, then it's not just incidental gas common everywhere in the Mississippi River Delta," said Ian MacDonald, a Florida State University oceanography professor. MacDonald, who has flown over the leak site roughly 20 times in the past five years, was an expert witness for environmental groups that sued Taylor Energy in 2012.

Representatives of Taylor Energy and the agencies overseeing the company's response work are scheduled to meet Tuesday in New Orleans. The government "believes that this meeting will likely have important ramifications with respect to the response to the ongoing oil release from the Taylor site," Justice Department lawyers wrote.

Regulators have warned that the leak could last a century or more if left unchecked.

A 2015 investigation by The Associated Press revealed evidence that the leak is worse than the company, or government, had publicly reported.

Presented with AP's findings that year, the Coast Guard provided a new leak estimate that was about 20 times larger than one cited by the company in a 2014 court filing.

Using satellite images and Coast Guard pollution reports, West Virginia-based watchdog group SkyTruth estimated in 2015 that between 300,000 and 1.4 million gallons (1 to 5 million liters) of oil had spilled from the site since 2004. The leak site is about 10 miles (16 kilometers) off Louisiana's coast.

The mudslide during Ivan buried Taylor Energy's wells under treacherous mounds of sediment. The company plugged nine wells at the site, but has cited experts as concluding it would be impossible to plug the other 16 wells and remove the contaminated soil without risking environmental damage.