A sign marks an access point to the Howard L. Mendall Wildlife Management Area on the western shore of the Penobscot River on Tuesday, Oct. 9, 2018. Credit: Bill Trotter / BDN

David Dietrich grew up in Orrington, along the Penobscot River, in the 1950s and ’60s.

“My brother and I were drawn to that river like filings to a magnet,” he said Tuesday. “But the river was not much more than a very polluted open sewer. The Clean Water Act changed that.”

Dietrich, who now lives in Blue Hill, said that he wants as much mercury as possible — which was deposited in the river by the defunct HoltraChem Manufacturing plant in his home town — to be removed.

“I want the Penobscot River to be as good as it possibly can be,” Dietrich said.

He was one of nearly two dozen people who appeared before U.S. District Judge John Woodcock on Tuesday to express support for a proposal to clean up mercury deposits in the Penobscot River estuary contaminated by the shuttered chemical plant.

The settlement, agreed to in March, calls for onetime plant owner Mallinckrodt US  LLC to spend between $187 million and $267 million for the cleanup. The work would include removing contaminated sediment from the river, capping some contaminated sediments with clean sediments, other beneficial environmental projects and long-term monitoring.

The plan calls for targeted but not widespread dredging of the river, which could disturb mercury deposits and redistribute them farther downstream.

Tuesday was the final day of a three day hearing on the settlement, and a day set aside for the public to weigh in on the plan.

No one spoke in opposition to the plan but some offered suggestions, including lowering the amount of mercury allowed in wildlife and adding sturgeon to the list of animals to be monitored. High levels of mercury in areas of the river south of Orrington have shut down commercial fishing in some areas and prompted warnings about the safety of eating fish from the river.

Under federal law, Woodcock must determine if the proposed settlement is fair, reasonable and in the public interest.

If the judge approves the plan, that would bring to an end a 21½-year legal battle over pollution in the Penobscot River that took place while HoltraChem operated on its banks from 1967 to 2000. The court case, brought by the Maine People’s Alliance and the Natural Resources Defense Council in 2000, is the oldest pending case in federal court in Maine.

John Dieffenbacher-Krall of Old Town was executive director of the Maine People’s Alliance in 2000 and filed the original complaint with the court, he said Tuesday. He told Woodcock that the settlement is fair, reasonable and in the public interest.

“The consent decree before this court is the product of 21 years of litigation and thousands of hours of time spent by the plaintiffs to address the serious harm caused by Mallinckrodt’s pollution. I am pleased that the parties are now prepared to work together on addressing that harm instead of battling in federal court whether a harm exists and, if so, what can be done about it.”

He said after the hearing that when the lawsuit was filed, state agencies, including the Department of Environmental Protection, were addressing the cleanup of the site where the plant operated, but not the contamination in the river.

Penobscot Nation Ambassador Maulian Dana did not attend the hearing but submitted written testimony supporting the proposed clean-up plan. She said that tribal members had recently voted to make the Penobscot River a citizen of the nation.

“We have sustenance fishing rights but can’t live on the fish [due to elevated mercury levels],” she said. “We can not afford to go backwards.”

She urged Woodcock to act quickly “to remedy the abuse the river has been a victim of.”

Mark Robinson, a spokesman for Mallinckrodt, praised the process after Tuesday’s hearing.

“There’s been a lot of transparency,” he said. “It is clear that all parties think this is a fair and reasonable remedy. It is important that the people in communities along the river see that.”

Woodcock did not say when he would issue a final ruling on the settlement. Lawyers have until Nov. 4 to file their final briefs, and he will issue a decision some time after that.