An oil leak was spotted off the coast of Plaquemines Parish on Thursday. The Coast Guard is overseeing a multi-agency response to the spill.

Authorities were using skimmers and remote vehicles to respond to an oil leak off the coast of Plaquemines Parish on Monday, with more than a million gallons having potentially been spilled, the Coast Guard said.

The total volume of spilled crude was unclear, but the Coast Guard said initial engineering calculations determined the potential amount at 1.1 million gallons. A slick of three to four miles wide was spotted on Thursday, when the spill was first reported, NOAA says.

The leak is near the Main Pass Oil Gathering company's pipeline system. MPOG is owned by Houston-based Third Coast, which did not immediately respond to a request for comment. The site is located about 19 miles offshore, south of the Chandeleur Islands and to the east of the Mississippi River.

Three skimming vessels were working to recover oil from the surface, the Coast Guard said. Remotely operated vehicles were searching for the spot of the pipeline leak, but were so far unsuccessful.

Overflights were also being employed and two Coast Guard cutters were on the scene. The oil had not reached the shore, according to the Coast Guard.

The 67-mile pipeline was closed at 6:30 am on Thursday, the Coast Guard says. The leak was reported to the National Response Center at 9:10 am the same day by Third Coast, with an oil sheen spotted about 10 minutes earlier, NOAA says. It was not clear if an earlier report had been made to the Coast Guard.

The cause remains under investigation. The Coast Guard is overseeing a multi-agency response to the spill.

In August 2022, Third Coast announced MPOG had completed construction of a 6.5-mile, 18-inch pipeline with a capacity of up to 80,000 barrels per day.

The 2010 BP Deepwater Horizon incident off Louisiana's coast spilled around 134 million gallons.

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