Reports of oil surfacing near the site of the Deepwater Horizon explosion are raising questions about its source and whether it is related to last year’s oil spill in the Gulf of Mexico – one of the worst environmental disasters in US history.

A patch of oil was documented last week about a quarter-mile northeast of the Macondo wellhead leased by BP. That site was plugged in July 2010 after about 4.9 million barrels (206 million gallons) of oil leaked into the Gulf.

On Wednesday, reporters from the Mobile, Ala., Press-Register published photographs and video of their discovery on the news organization’s website, which was in response to surveillance flights conducted the week before by two environmental groups – the Gulf Restoration Network and On Wings of Care. The Press-Register reported witnessing ‘blobs of oil rise to the surface and bloom into iridescent yellow patches