The Ironbound neighborhood of Newark, N.J., has been revitalized. The tree-lined river that runs beside it has not.

Half a century ago, the herbicide Agent Orange was manufactured along the banks of the Passaic River. Poison hosed off factory floors drained into the waterway, where it sank to the bottom and became toxic sludge. The estimated cost of cleaning it up and compensating for environmental damage could run as high as $11.8 billion.

Who will pay the bill? That’s now a question for a federal bankruptcy court in Delaware. And its answer could determine whether other companies with billions of dollars in environmental liabilities can use the U.S. bankruptcy system to avoid them.

YPF SA, an Argentine state oil company, took over the Agent Orange site in 1995 as part of its acquisition of Maxus Energy Corp., an oil-and-gas company. Over the years, YPF sold off Maxus’s oil-and-gas holdings, then put the unit into bankruptcy in 2016. YPF says it isn’t responsible for covering the cost of the cleanup. And the bankrupt subsidiary, it says, has no money to pay for it.

Other interested parties, including another company that shares the liability, are up in arms over the maneuver. They say the subsidiary was a puppet company emptied of value and left to take the fall for the Passaic River. Creditors sued YPF in June, alleging it improperly bled Maxus dry, intending to use its subsidiary’s bankruptcy filing to ditch its cleanup obligations.