Biggest Environmental Settlements: PFAS, Cleanup, and Clean Air Act

The biggest environmental settlements of 2024 were led by a roughly $2 billion deal with Cummins over diesel emissions cheating, a record $241.5 million Clean Air Act agreement with Marathon Oil, and PFAS drinking water settlements with 3M and the DuPont group that together make up to $13.6 billion available to public water systems. Federal enforcement that year produced $1.7 billion in total EPA penalties across more than 1,800 civil cases, the highest totals since 2017.¹ A youth-led constitutional climate case in Hawai’i and several large Superfund cleanups rounded out a year that now looks like an outlier against sharply reduced federal enforcement in 2025.

Cummins Diesel Engine Settlement

The single largest environmental enforcement action of the year resolved allegations that Cummins Inc. installed software designed to manipulate emissions testing in diesel engines supplied to Fiat Chrysler for RAM 2500 and 3500 pickup trucks. The total value exceeded $2 billion, and the civil penalty alone reached $1.675 billion, roughly 86% of EPA’s entire fiscal year penalty total.²³

Two proposed consent decrees were filed in the U.S. District Court for the District of Columbia on January 10, 2024, covering about one million vehicles: more than 630,000 trucks from model years 2013 through 2019 containing actual defeat devices, and more than 330,000 trucks from model years 2019 through 2023 containing undisclosed auxiliary emission control devices.² Cummins must recall and repair at least 85% of the older trucks within three years through free software updates, working with Fiat Chrysler’s dealer network.⁴

Beyond the penalty, Cummins committed more than $325 million to mitigation. That includes roughly $175 million to the California Air Resources Board for emission reduction programs, replacement of 27 high-emitting diesel locomotive engines, and funding for 50 projects to reduce locomotive idling.² Enhanced testing, internal audits, and corporate compliance measures were also required.⁴

Marathon Oil’s Record Clean Air Act Penalty

On July 11, 2024, the DOJ and EPA announced a $241.5 million settlement with Marathon Oil covering Clean Air Act violations at oil and gas production facilities on the Fort Berthold Indian Reservation in North Dakota. The $64.5 million civil penalty was the largest ever for stationary source violations of the Clean Air Act.⁵

The government alleged violations at nearly 90 facilities, including artificially low emissions estimates submitted to avoid permitting requirements and excessive flaring of waste gases, including methane. Additional allegations involved failure to comply with storage tank rules at 66 oil facilities and unauthorized releases of volatile organic compounds, carbon monoxide, and greenhouse gases.⁶

Marathon agreed to spend an estimated $177 million on compliance measures across more than 200 facilities, projected to cut over 2.25 million tons of carbon dioxide equivalent emissions and nearly 110,000 tons of volatile organic compounds over five years.⁵ The company must obtain permits for existing and new facilities, conduct ongoing emissions audits, and halt production whenever emissions limits are exceeded or flares malfunction. Marathon also agreed to buy two infrared cameras for the Mandan, Hidatsa and Arikara Nation to use during facility inspections, and the compliance obligations remain binding regardless of ConocoPhillips’s then-pending acquisition. Marathon did not admit liability.⁶

PFAS Drinking Water Settlements

Two class action settlements over PFAS contamination in public drinking water advanced through federal court in 2024, together making up to $13.6 billion available to affected water systems nationwide.⁷

3M

The U.S. District Court in Charleston, South Carolina, granted final approval to the 3M settlement on March 29, 2024. The nominal cap is $12.5 billion, with a pre-tax present value of about $10.3 billion, paid over 13 years from 2024 through 2036. The settlement covers any U.S.-based public water supplier that has detected PFAS at any level, or that may detect it in the future. Payments are front-loaded: $2.9 billion in 2024, $1.8 billion in 2025, then varying amounts through 2036.⁸

DuPont, Chemours, and Corteva

The DuPont group settlement totals $1.185 billion, with Chemours responsible for about 50% (roughly $592 million), DuPont contributing approximately $400 million, and Corteva about $193 million. The full amount was deposited into a water district settlement fund shortly after preliminary court approval.⁹

One important difference between the two agreements: the DuPont settlement requires testing of all water sources for a public water system and reporting of any measurable PFAS concentration, regardless of whether it exceeds the minimum reporting level. Systems with pre-December 2021 results showing no detection must retest or risk disqualification.¹⁰

Deadlines for Water Utilities

Water utilities that have not yet filed face hard Phase 2 deadlines in 2026: March 31 for testing claims, June 30 for DuPont treatment claims, and July 31 for 3M treatment claims.⁷ Municipalities that miss these deadlines forfeit their share and waive their right to sue 3M and DuPont later over PFAS drinking water contamination.¹¹

Hawai’i Youth Climate Settlement

On June 20, 2024, Hawai’i State Environmental Court Judge John Tonaki approved a settlement in Navahine F. v. Hawai’i Department of Transportation requiring the state to decarbonize its transportation system. The case, brought by youth plaintiffs, was the first constitutional climate lawsuit in the United States to reach a binding settlement, committing the Hawai’i Department of Transportation to zero emissions from ground, interisland sea, and air transportation by 2045.¹²¹³

The settlement is rooted in the Hawai’i Constitution’s public trust doctrine and the right to a clean and healthful environment, and formally recognizes children’s constitutional rights to a “life-sustaining climate.”¹³ Specific mandates include:

HDOT must produce a statewide decarbonization plan within one year that maps emissions reductions over the next 20 years, with interim targets for 2030, 2035, and 2040.
The state must complete pedestrian, bicycle, and transit networks within five years and dedicate at least $40 million to expanding the public electric vehicle charging network by 2030.
A dedicated unit within HDOT will coordinate greenhouse gas reduction and climate adaptation, and emissions and vehicle miles traveled impacts must be built into infrastructure budgeting.
A volunteer youth council will advise on implementation.

The court retains jurisdiction until December 31, 2045, or until the zero emissions target is met, with dispute resolution procedures built into the agreement.¹⁴

Superfund Cleanup Settlements

Lower Duwamish Waterway

In 2024 the EPA issued a $96 million unilateral administrative order to begin in-water construction at the Lower Duwamish Waterway Superfund site in Seattle, with construction starting that November.¹⁵ A broader consent decree valued at approximately $668 million followed in March 2026. Under it, the Lower Duwamish Waterway Group (The Boeing Company, the City of Seattle, and King County) will dredge, cap, and otherwise remediate roughly 177 acres of a five-mile river segment contaminated with 41 hazardous substances including PCBs, arsenic, dioxins, and furans. The work is expected to take at least 10 years, with about $130 million from other private responsible parties and $140 million from federal agencies on top.¹⁶

Passaic River

In December 2024, a federal judge in New Jersey approved a $150 million consent decree between the EPA and 82 potentially responsible parties for the dioxin-contaminated lower Passaic River cleanup. The settling firms include Chevron, Pabst Brewing Company, and Paramount Global.¹⁷ An allocation firm determined that Occidental Chemical, the corporate successor to Diamond Alkali, bore just under 85.1% of total responsibility, an estimated $1.6 billion liability before cost overruns. The $150 million from the other parties represents about 8% of the total estimated cleanup cost for the lower river.

OxyChem, which has already spent $260 million on design and preparation for the lower eight miles, challenged the allocation’s fairness. Judge Madeline Cox Arleo rejected those arguments, calling the $150 million “significantly more than their estimated liability.”¹⁸ OxyChem appealed to the Third Circuit in July 2025, and remediation work on the river has not yet begun.

Cahokia Heights Sewer Consent Decree

A December 2024 Clean Water Act consent decree addressed decades of raw sewage flooding in Cahokia Heights, Illinois, a community of roughly 18,000 residents formed in 2021 from the merger of three smaller municipalities. The federal complaint alleged more than 300 unauthorized sewage discharges into local waterways since November 2019, all without the required federal permits.¹⁹ An ongoing health study found that more than 40% of adults in the community tested positive for the stomach infection caused by H. pylori, linked to chronic exposure to sewage-contaminated floodwater.²⁰

The city must spend an estimated $30 million on a two-phase infrastructure program. Phase 1 runs through 2029 and includes more than 80 capital projects, among them a $13.5 million interceptor to reroute wastewater, plus a full cleaning of the 90-mile sewer system. Phase 2 extends through 2035 for additional investigation and repairs.¹⁹ Community advocates and the residents’ attorneys called the timeline unreasonably long, arguing many vulnerable residents who have endured sewage-filled homes for years may not live to see the work completed. Public comments led to revisions before the court entered the final agreement in January 2026.²¹

Other Notable 2024 Actions

CQC Impact Investors Carbon Credit Fraud

In October 2024, a coordinated federal action targeted CQC Impact Investors (C-Quest), a carbon credit developer that had manipulated data from cookstove and lightbulb projects in Africa, Central America, and Southeast Asia to inflate verified carbon credits. The company determined that about six million credits across 27 projects were fraudulently reported and had to be cancelled, roughly 30% of its previously certified offsets. C-Quest used the inflated data to raise $250 million from institutional investors, of which $170 million was paid out before the fraud came to light.²²

The SEC issued a cease-and-desist order and the CFTC imposed a $1 million civil penalty. The U.S. Attorney’s Office for the Southern District of New York unsealed criminal charges against CEO Kenneth Newcombe and head of carbon accounting Tridip Goswami for wire fraud, commodities fraud, and conspiracy. The company’s chief operating officer pleaded guilty and began cooperating.²²

Walmart Hazardous Waste

Walmart agreed to a $7.5 million settlement with the California Attorney General’s Office and district attorneys from 12 counties over illegal disposal of hazardous and medical waste at more than 300 stores and distribution centers statewide. Audits conducted between 2015 and 2021 found Walmart discarding toxic aerosols, liquid wastes like spray paints and pesticides, and medical waste including over-the-counter drugs in regular trash bins bound for landfills not equipped to handle them. It was Walmart’s second such case in California; a 2010 judgment covering similar conduct included an eight-year injunction that officials said the company continued to violate.²³

Sasol Chemicals

In April 2024, Sasol Chemicals settled with the EPA for $1.44 million over chemical accident prevention violations at its facility in Westlake, Louisiana, where an October 2022 fire had triggered a shelter-in-place order. The settlement required Sasol to develop safe work practices for pressure testing, improve process hazard analysis procedures, upgrade safety detection systems, and resolve overdue compliance audit findings.²⁴

Tyson Foods Greenwashing

In November 2025, Tyson Foods settled a lawsuit brought by the Environmental Working Group in D.C. Superior Court challenging its “climate-smart beef” marketing and its pledge to reach net-zero greenhouse gas emissions by 2050. Under the five-year settlement, Tyson is barred from making or repeating claims about net-zero ambitions, “climate-smart” or “climate-friendly” beef, or its “Brazen Beef” product line unless a mutually agreed independent expert verifies the claims as “substantiated and valid.” To qualify, Tyson must show a “reasonable probability” that its goals are “factually and practically achievable and not merely illusory” and that it has taken “demonstrable steps adequate to reach its stated goal.”²⁵ Financial terms remain confidential, and neither party may publicly claim the settlement proved or disproved whether the original marketing was misleading. The terms are more restrictive than those in a contemporaneous JBS settlement, which allowed JBS to continue referencing net-zero ambitions when framed as aspirational.

What Happened to Enforcement After 2024

The 2024 numbers now stand against a very different 2025. According to a February 2026 report from the Environmental Integrity Project, DOJ settled only 15 EPA-referred cases during the first year of the Trump administration (January 2025 to January 2026), compared to 71 in the Biden administration’s first year and 75 in Trump’s own first term. Judicial legal actions against polluters on EPA’s behalf fell 81% from the prior Trump term and 87% from the start of Obama’s second term.²⁶

A March 2025 memo from the acting head of EPA’s enforcement office required advance approval from a political appointee for any enforcement action that could “unduly burden” energy production. A December 2025 directive told enforcement staff to prioritize “compliance assistance” over formal enforcement and barred supplemental environmental projects that provide community benefits. Of the 40 judicial cases settled in 2025, 33 had been initiated by previous administrations.²⁷

The program numbers show the shift most clearly. Only one Clean Air Act consent decree was lodged between January 2025 and January 2026, against 26 during the equivalent period of the first Trump term. Superfund decrees fell from 31 to 7, and Clean Water Act decrees from 15 to 4.²⁸ At least a third of the lawyers in DOJ’s environment division left over the past year. The EPA called the criticism “erroneous” and said its focus is on “achieving swift compliance” rather than “overzealous enforcement intended to cripple industry.”²⁶

1
U.S. EPA. EPA FY 2024 End of Year Enforcement Results
2
DieselNet. Cummins Emissions Settlement
3
Earth and Water Group. FY 2024 Enforcement Results
4
California Air Resources Board. Cummins Settlement Frequently Asked Questions
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PBS NewsHour. Marathon Oil and EPA Reach $241 Million Settlement
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North Dakota Monitor. Marathon Oil Reaches $241.5M Settlement
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NRDC. PFAS Settlement Money for Water Utilities Poised to Evaporate
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3M Investor Relations. 3M Settlement With Public Water Suppliers to Address PFAS
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DuPont. Chemours, DuPont and Corteva Reach Comprehensive PFAS Settlement
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State of Maine AG. 3M and DuPont Settlement Info Sheet
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National League of Cities. PFAS Settlement Deadlines Updated
12
Governor of Hawai’i. Historic Agreement Settles Navahine Climate Litigation
13
Earthjustice. Historic Agreement Settles Hawaii Youth-Led Constitutional Climate Complaint
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Sabin Center for Climate Change Law. Navahine F. v. Hawai’i Department of Transportation
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U.S. EPA. Lower Duwamish Waterway Superfund Settlement Summary
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U.S. EPA. EPA Reaches $668M Settlement Agreement for Continued Cleanup of Lower Duwamish Waterway
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New Jersey Monitor. Judge Approves $150M Agreement for Passaic River Cleanup
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NJ Spotlight News. OxyChem Appeals Ruling It Must Pay Most of Passaic River Cleanup Costs
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U.S. EPA. Cahokia Heights Clean Water Act Case Summary
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St. Louis Public Radio. Cahokia Heights Must Complete $30 Million in Sewer Fixes
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Illinois EPA. Cahokia Heights Community Relations
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U.S. Securities and Exchange Commission. CQC Impact Investors Cease-and-Desist Order
23
KTLA. Walmart Ordered to Pay Millions for Disposing of Toxic Medical Waste
24
American Press. EPA $1.4M Settlement With Sasol Chemicals
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Bloomberg. Tyson Foods Agrees to Stop Marketing Its Beef Products as Green
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NPR. EPA Trump Enforcement
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Environmental Integrity Project. 2025 Environmental Enforcement Report
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Public Employees for Environmental Responsibility. PEER Enforcement Report