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Pipeline Spill Releases Up to 1.1 Million Gallons of Oil off Louisiana

Oil slick off Pass a Loutre (USCG)
Oil slick off Pass a Loutre (USCG)

Published Nov 20, 2023 6:10 PM by The Maritime Executive

The U.S. Coast Guard says that a pipeline spill off the Mississippi River Delta has released up to a maximum of 1.1 million gallons of oil into the environment, based on engineering calculations. If verified at the upper end of the potential release range, this would be a significant volume, equivalent to roughly 0.5 percent of the Deepwater Horizon blowout or 10 percent of the Exxon Valdez spill.  

Over the weekend, a unified command set up by the Coast Guard organized overflights to establish the extent of the spill. A Thursday afternoon overflight identified a slick about four miles wide, with patches of dark oil throughout. 

NOAA's analysts predict that it is moving off to the southwest, away from Louisiana's shores. By Sunday, the slick was reduced to intermittent surface sheening. The Coast Guard said that assessment flights continue, alongside surface monitoring by Coast Guard cutter assets. 

The pipeline operator shut down MPOG on Thursday morning at 0630, and an oil sheen was spotted at 0900. Operator Third Coast Midstream Pipeline notified NOAA's National Response Center at 0910. 

The spill has ceased and skimmers are working on cleanup. The breach in the pipeline has not been found, and ROV surveys are still under way in an attempt to locate it, weather permitting. The location is believed to be about 20 miles off Pass a Loutre. 

The pipeline in question is the Main Pass Oil Gathering (MPOG) line, which handles about 80,000 barrels per day of crude from the shallow-water fields near Main Pass and Viosca Knoll. MPOG is currently a subsidiary of Texas-based oil firm Third Coast, formerly known as American Midstream.