NEW ORLEANS -- More than 88,000 gallons of oil spilled into the Gulf of Mexico after one of Shell's offshore drilling lines sprang a leak Thursday morning, prompting U.S. Coast Guard vessels to assist the oil company in cleanup efforts.
About 88,200 gallons of oil were released roughly 90 miles off the coast of Louisiana, the company said Friday.
About 12:30 a.m. Friday, a remote-operated submarine vessel identified one of Shell's flow lines as the source of the leak.
"The section of flow line has been isolated, and the ROV is continuing to assess the subsea infrastructure to confirm no additional discharge points," the Coast Guard said in a press release.
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The flow line was connected to four wells and Shell's Brutus platform, which floats in seas that are about a half-mile deep in the Green Canyon area of the Gulf.
Shell said the leak has been contained and the wells on the site were shut in. It also said drilling at the site was stopped.
Shell and the Coast Guard have mobilized 137 personnel for unified response efforts, along with vessels to search for oil that can be safely skimmed from the water's surface. Shell also contracted aircraft to provide aerial assessment of the affected area.
The Coast Guard and Shell have jointly agreed that skimming is the safest and most effective oil recovery option at this time.
Meanwhile, environmental groups said this latest spill was another example of why offshore drilling should be banned. Activists plan to hold a march in Washington on Sunday to demand an end to drilling and used this new spill as further evidence.
"It's unacceptable that oil spills have been permitted to become the status quo in the Gulf," said Michael Brune, the Sierra Club's executive director, in a statement. "We have allowed the region to be perpetually treated as a sacrifice zone."
Shell did not directly respond to the complaints of environmental groups. In a statement, Kimberly Windon, a Shell spokeswoman, said, "No release is acceptable, and safety remains our priority as we respond to this incident."
Spills happen every year in the Gulf. This new spill is classified as medium in size under Coast Guard guidelines.
Since 2012, there have been 147 spills and about 516,900 gallons of oil spilled in the Gulf, according to figures from the Bureau of Safety and Environmental Enforcement, the agency that oversees drilling.
But scrutiny of the offshore industry's spills has increased since BP's catastrophic oil spill in 2010 when an out-of-control well leaked for 87 days, releasing millions of gallons of oil. Eleven workers were killed and many more injured when the blowout of the well caused the Deepwater Horizon drilling rig to explode and sink.
BSEE, the regulatory agency, said there have been no reports of injuries. In a statement, the agency said its investigators were at the Brutus platform to find out what caused the leak. The agency said it would review Shell's repair plans.
BSEE Director Brian Salerno said the agency would assess if improvements to "subsea infrastructure technology" should be made as a result of the incident.
The Associated Press, contributed to this report.