Using sonar technology and a newly developed method of analyzing oil and gas bubbles rising through the water, scientists determined that the plumes are the result of oil and gas released from multiple wells. They also found that as many as 108 barrels of oil, or just over 4,500 gallons, have spilled into the Gulf each day as a result of the episode.

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“While it is feasible that the heavily oiled sediments in and around the erosional pit could be contributing to oil in the water column, the chemical nature and volume of oil and gas measured precludes sediments from currently being the major source of oil to the marine environment,” the report says.

The researchers also noted that their findings indicated lower levels of leakage than a handful of other recent estimates. Government attorneys in a federal court filing last year, for example, estimated that up to 30,000 gallons were leaking daily from the destroyed wells.

The study comes as the Trump administration works to roll back a key offshore-drilling safety regulation that was put in place after the 2010 Deepwater Horizon explosion in the Gulf of Mexico. That disaster, the worst oil spill in United States history, killed 11 people and released an estimated 4.9 million barrels into the sea.