The U.S. Coast Guard says as much as 1.1 million gallons of oil, approximately 26,000 barrels, may have spilled into the Gulf of Mexico following a pipeline leak on Thursday off the coast of Louisiana. The source of the spill from the 67-mile-long underwater pipeline owned by Main Pass Oil Gathering and operated by Third Coast Infrastructure LLC remained unknown at the time of writing on Monday, with the Coast Guard continuing to investigate. The pipeline spill was confirmed by Main Pass Oil on Thursday, prompting immediate Coast Guard…