BANGOR – A Maine judge heard the final arguments Wednesday in a federal case about whether a chemical company responsible for dumping mercury from a closed plant will be required to clean up nearby waterways.

The case concerns the banks of the Penobscot River and the mouth of Penobscot Bay.

Maine’s high court ruled in 2014 that Mallinckrodt US had to carry out an estimated $130 million cleanup on the site of the former HoltraChem Manufacturing Co. Maine People’s Alliance and the Natural Resources Defense Council want Mallinckrodt to be forced to clean up the mercury released by the now-defunct Orrington plant in the 1960s and 70s.

The parties are now waiting for a U.S. District Court judge in Bangor to issue an order.

Peter Lehner, the resources council’s executive director, said the mercury threatens both people and wildlife. Mallinckrodt lawyers argued before the trial that the river is less contaminated than a study suggests.