A pipeline leak off the coast of Louisiana that dumped the equivalent of two Olympic-size swimming pools of crude to the Gulf of Mexico has forced seven drillers to shut in production, according to the US Coast Guard. 

There is no timeline for restarting output as the Coast Guard continues to search for the source of the release, Captain Kelly Denning said at a press briefing Tuesday. Rough seas and strong winds that slowed work in the first few days have subsided, allowing for cleanup and work to locate the source to advance. 

The 26,000-barrel spill was first reported on Thursday when pipeline operator Main Pass Oil Gathering Co. reported a drop in pipe pressure, an indication of a leak. Denning said it’s unclear whether Main Pass is the company responsible “as there are multiple pipeline operators in the area.”

The names of the oil-producing companies affected were not released.

The spill hasn’t impacted vessel traffic and the oil hasn’t reached the shore, the Coast Guard said. On Monday, Heavy Louisiana Sweet crude oil produced in the area — the same kind that was spilled — traded at a premium of $2.70 to West Texas Intermediate oil, the highest premium since August, according to Link Data Services. 

Environmentalists reacted with alarm Tuesday, saying the potential peril to dolphins, birds and other animals underscores a need to halt new offshore oil drilling. “The Biden administration needs to wake up and stop letting oil companies expand their heavy footprint in our sensitive coastal waters,” said Kristen Monsell of the Center for Biological Diversity.