Source of Million-Gallon Spill off Mississippi Delta Remains a Mystery

A skimmer recovers oil from the MPOG incident last week (USCG)

Published Nov 28, 2023 4:13 PM by The Maritime Executive

The U.S. Coast Guard and its response partners are still looking for the source of a large-scale oil spill near the Main Pass Oil Gathering pipeline, just off the eastern side of the Mississippi Delta. 

On the morning of Nov. 16, at 0630, pipeline operator Third Coast shut down MPOG. An oil sheen was spotted later in the morning, and Third Coast notified federal authorities of a spill. 

The oil release ceased, and no new oil has been spotted on the water since Nov. 20. Based on engineering calculations, the authorities estimate the size of the spill at up to 1.1 million gallons.

Skimmers were deployed to target concentrated areas of slick for cleanup and a small volume of oil-water mixture was recovered. The spill disippated quickly into a light sheen and drifted offshore, away from vulnerable coastal wetlands. Recent wildlife and shoreline assessments have identified no detectable impact to wildlife.

The cause and source of the incident remain under investigation, the Coast Guard said Tuesday. About 40 miles of the MPOG line have been inspected already, and no signs of damage or leakage have been detected. Remotely operated vehicles (ROVs) and divers are still surveying multiple pipelines in the area, and ROV surveys have examined about six miles of surrounding pipelines near MPOG, with no results. 

The unified command emphasized that no volunteers are needed at the moment. 

An estimated three percent of Gulf oil production has been shut in by the pipeline shutdown, and the Coast Guard has yet to announce a timeline for resumption of service.