Proposed Settlement Aims to Clean Up Mercury in the Penobscot River Estuary

After two decades of litigation, a proposed consent decree from Maine People’s Alliance, NRDC, and Mallinckrodt US LLC could accelerate the recovery of Maine’s largest river.

The Penobscot River in Maine

Justin Lewis/Getty Images

This blog was co-authored with Jesse Graham of Maine People’s Alliance.

Today, Maine People’s Alliance (MPA), NRDC, and Mallinckrodt US LLC filed a proposed consent decree to settle litigation over mercury contamination in the Penobscot River estuary. This settlement, once reviewed and approved by the court, would conclude more than two decades of litigation and court-ordered studies of the river, benefit the environment, and accelerate the recovery of the river.

Here are the quick facts:

  • Mallinckrodt will pay at least $187 million, and up to $267 million, for activities to remediate mercury in the Penobscot River estuary.
  • To date, Mallinckrodt has paid over $30 million to fund court-ordered studies of the river, and these studies informed the design of the planned remediation.
  • Cleanup activities will be directed by an experienced, independent trustee.
  • Work will include at least capping contaminated sediments with clean sediments, targeted removal of contaminated sediments, beneficial environmental projects, and long-term monitoring.
  • All remediation work will go through applicable local, state, and federal permitting and review procedures.
  • The court will establish a process for reviewing the proposed settlement.
  • The settlement will take effect only if the court approves it.

Under the proposed consent decree, Mallinckrodt will fund two trusts to implement remediation work in the river and beneficial environmental projects. Mallinckrodt will deposit $187 million into the trusts and will contribute up to an additional $80 million if specific contingencies occur. MPA, NRDC, and Mallinckrodt have selected an independent trustee, the Greenfield Environmental Trust Group, to manage the trusts and direct the remediation work. Greenfield has 30 years of experience managing complex environmental response trusts and cleanups around the country.

The three parties anticipate that the remediation work will reduce mercury concentrations across the estuary, but they also recognize that because the Penobscot River is a complex ecosystem, exact benefits of any particular remedial measure may be difficult to predict and measure with certainty. Most important, the parties negotiated this settlement to avoid further litigation and delays and instead begin cooperative remediation of the river as soon as possible.

Now that the proposed consent decree has been lodged with the U.S. District Court for the District of Maine, the court will review and determine whether it is fair, reasonable, and in the public interest—and it will take effect only if the court approves it. The parties anticipate that the court will establish a process for public input.

Background on MPA and NRDC v. HoltraChem Manufacturing Co., LLC, and Mallinckrodt US LLC

Amec Foster Wheeler, September 2018, Phase III Engineering Study Report, Fig 1.1

The Penobscot River estuary in Maine extends from the head of tide in the vicinity of Bangor to the northern end of Penobscot Bay in the vicinity of Fort Point and Cape Jellison. Beginning in 1967, a former chlor-alkali facility in Orrington released mercury into the Penobscot River estuary. The facility was owned and operated by Mallinckrodt’s corporate predecessor until 1982, then by Hanlin Group, Inc., and later by HoltraChem Manufacturing Company, LLC. In 2000, MPA and NRDC sued Mallinckrodt and HoltraChem under the Resource Conservation and Recovery Act, asking the court to order an independent study to evaluate the harms from the mercury contamination and then order appropriate remedial measures to clean up the river. The court found that Mallinckrodt was liable as a source of the mercury and that the mercury could endanger health and the environment. A court-appointed panel of scientists studied the mercury contamination in the estuary, finding elevated concentrations of mercury in sediment and wildlife and recommending remedial action to clean up the river.

Informed by the study’s results, the Maine Department of Inland Fisheries and Wildlife in 2011 advised pregnant women and young children not to consume waterfowl taken along the lower Penobscot River due to elevated concentrations of mercury in black duck tissue. In 2014, the Maine Department of Marine Resources closed lobster and crab fisheries north of Fort Point because of mercury concentrations in lobster and then expanded the closed area in 2016.

After a trial in 2014 to evaluate the study’s findings, the court appointed an engineering firm to identify cost-effective remedial actions that would accelerate the recovery of the river. The structure of the proposed consent decree is generally modeled on the engineering firm’s recommendations, which were filed with the court in October 2018. In total, the extensive court-ordered scientific and engineering studies lasted more than a decade, at a cost of over $30 million.

Details of the Proposed Consent Decree

Before going further, let’s define some of the possible remediation actions:

  • Beneficial Environmental Projects: Projects that provide environmental or public benefits to affected communities or the environment
  • Capping: The placement of clean materials over contaminated sediment to create a barrier between contamination and the water column
  • Enhanced Monitored Natural Recovery: The addition of clean sediment naturally dispersed by tides and currents, so that the clean sediment mixes with contaminated sediments, thereby diluting contamination and accelerating natural recovery processes
  • Long-Term Monitoring: Repeated measurements of mercury levels in wildlife, sediments, and water over decades
  • Removal: Excavation or dredging of contaminated materials to remove contamination

As mentioned above, under the consent decree, Mallinckrodt will fund two trusts that will implement remedial measures intended to accelerate the river’s recovery. Mallinckrodt will deposit $187 million into the trusts over the next seven years and, if certain contingencies occur related to remediation and disposal costs, will pay up to an additional $80 million to the trusts. The court will retain jurisdiction over the consent decree throughout its implementation. Of course, all remedial actions will have to comply with applicable local, state, and federal permitting and other regulatory requirements.

The trusts will implement five categories of remedial actions:

1. Capping in the Orrington Reach
The consent decree provides at least $50 million for capping approximately 130 acres of intertidal sediments along the east bank of the Penobscot River in the vicinity of Orrington. Clean sediment will be added to cover areas that have elevated concentrations of mercury.

2. Targeted Removal of Mobile Sediment
The consent decree also provides at least $70 million for targeted removal of contaminated sediments and wood waste that have been trapped in the estuary by tides and currents. (The specific locations and amount of removal will be determined by the trustee.) Materials removed from the estuary will be beneficially reused if possible or safely disposed of, outside of the aquatic environment.

3. Remediation in the Orland River and East Channel
While the specific remedial actions in this region will be determined by the trustee, the consent decree provides $30 million for remediation in the region that includes the Orland River and the channel east of Verona Island. 

4. Beneficial Environmental Projects
In addition to its focus on remediation in the estuary, the consent decree provides $20 million for projects that will benefit the environment and the communities affected by the contamination. The specific projects will be determined at a later date.

5. Long-Term Monitoring
Finally, the consent decree provides at least $10 million for 30 to 45 years of monitoring of mercury concentrations in sediment, water, and wildlife. The length of the monitoring program will depend in part on the results of the monitoring.

Public Participation

MPA, NRDC, and Mallinckrodt are reaching out to notify interested parties about the decree and explain the components of the proposed remediation. All the parties strongly encourage the public’s participation in reviewing the decree (which is available at and in any public input process that the court establishes.

More information about the court-ordered studies of the Penobscot River estuary is available at

Filing this proposed settlement is a major milestone in the fight to clean up toxic mercury pollution. If approved by the court, this settlement will turn the page on more than two decades of litigation and start a new chapter of cooperative work to accelerate the recovery of the Penobscot River estuary. That is good news for wildlife, and all of the people who live near, work on, fish in, and enjoy this special place.

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