Dredging the Cape Fear River: PFAS Risks and Regulatory Implications for North Carolina

Introduction

The recent NC Newsline report detailing the U.S. Army Corps of Engineers’ plan to dredge the Cape Fear River raises immediate concerns for anyone working on PFAS contamination in North Carolina. As a scientist who has spent years investigating the fate and transport of per‑ and polyfluoroalkyl substances in aquatic systems, I view this proposal through a dual lens: the engineering necessity of maintaining navigable channels and the environmental imperative to avoid re‑releasing legacy pollutants that threaten drinking‑water supplies. In this editorial, I will contextualize the dredging proposal within the broader PFAS landscape of the Cape Fear basin, examine the relevant federal and state regulatory frameworks, and outline what municipal water systems and policymakers should consider moving forward.

Why the Cape Fear River Matters for PFAS

The Cape Fear River is not merely a transportation corridor; it is a primary source of drinking water for over 500,000 residents in Wilmington, Fayetteville, and surrounding communities. Since the early 2000s, numerous peer‑reviewed studies have documented the presence of PFAS—particularly perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and the GenX compound (hexafluoropropylene oxide dimer acid)—in the river’s surface water, sediments, and biota. These contaminants trace back largely to historic discharges from the Chemours Fayetteville Works facility, which operated upstream of the river’s main stem.

Sediments act as a secondary reservoir for PFAS, especially for the longer‑chain compounds that sorb strongly to organic matter. While the river’s water column concentrations have declined following regulatory interventions and treatment upgrades at the Fayetteville Works site, sediment cores collected in recent years still show detectable PFAS levels. Disturbing these deposits through mechanical dredging could resuspend particle‑bound PFAS, temporarily elevating dissolved concentrations downstream and potentially compromising the efficacy of existing treatment barriers.

EPA’s PFAS Maximum Contaminant Levels and Their Relevance

In April 2024, the U.S. Environmental Protection Agency (EPA) finalized enforceable Maximum Contaminant Levels (MCLs) for six PFAS in drinking water: 4 parts per trillion (ppt) for PFOA and PFOS, 10 ppt for PFNA, PFHxS, and PFBS, and a Hazard Index approach for mixtures of PFNA, PFHxS, PFBS, and GenX. These MCLs are legally binding for all public water systems subject to the Safe Drinking Water Act.

For the Cape Fear River watershed, the implication is clear: any activity that increases PFAS concentrations in source water must be evaluated against these thresholds. While the Army Corps’ dredging operation is not a direct discharge, the resuspension of contaminated sediments could lead to short‑term spikes that challenge treatment plants designed to meet the new MCLs. Municipal utilities such as the Cape Fear Public Utility Authority (CFPUA) have already invested in granular activated carbon (GAC) and ion‑exchange systems to achieve compliance; however, sudden increases in influent PFAS load could shorten media life and raise operational costs.

North Carolina’s State‑Level PFAS Initiatives

North Carolina has been at the forefront of state‑level PFAS regulation. The NC Department of Environmental Quality (DEQ) adopted a PFAS Action Plan in 2020, establishing health‑based goals for PFOA and PFOS at 10 ppt each and requiring monitoring of PFAS in public water supplies. In 2022, the DEQ issued a permit modification to Chemours Fayetteville Works that mandated further reductions in airborne and aqueous PFAS emissions, reflecting the state’s commitment to source‑control strategies.

Importantly, the DEQ has also emphasized sediment management as part of its PFAS mitigation toolkit. Guidance documents released in 2023 advise that any dredging or sediment‑removal activity in PFAS‑impacted waters should include a sediment‑characterization study, a resuspension‑modeling analysis, and a mitigation plan that may involve temporary water‑treatment upgrades or controlled release windows. The Army Corps’ current proposal, as described in the NC Newsline article, does not appear to have publicly disclosed such a PFAS‑focused sediment assessment, which represents a gap that state regulators should address before permitting proceeds.

Potential Impacts on Municipal Water Systems

Municipal water systems drawing from the Cape Fear River face a layered challenge. First, they must contend with the baseline PFAS load already present in the river. Second, they must accommodate variability introduced by storm events, agricultural runoff, and now, potentially, dredging‑induced sediment resuspension. Third, they must remain compliant with the EPA’s MCLs, which became enforceable in 2024 for the largest systems and will extend to smaller systems by 2026.

If dredging proceeds without adequate safeguards, the following scenarios could arise:

1. Short‑term concentration spikes – Resuspended sediments could elevate dissolved PFAS levels for hours to days, depending on flow conditions and sediment characteristics.
2. Increased treatment demand – GAC beds may experience accelerated breakthrough, necessitating more frequent change‑outs and raising operational expenditures.
3. Public‑confidence risks – Even transient exceedances of health‑based goals can erode trust, particularly in communities that have already experienced PFAS‑related advisories.

To mitigate these risks, I recommend that the Army Corps, in coordination with NC DEQ and affected utilities, conduct a site‑specific sediment PFAS profile prior to dredging, employ hydrodynamic modeling to predict plume dynamics, and consider adaptive management approaches such as timed dredging windows during low‑flow periods or the deployment of silt curtains to limit contaminant spread.

Connecting to Broader NC PFAS Policy

The Cape Fear River dredging debate sits at the intersection of infrastructure maintenance and environmental protection—a recurring theme in North Carolina’s PFAS narrative. The state’s PFAS Testing Act of 2021 mandated statewide sampling of drinking water, revealing detectable PFAS in over half of the tested systems. Subsequent legislative efforts have focused on funding for treatment upgrades, holding polluters accountable, and establishing stringent discharge limits.

From a policy perspective, any federal project that could exacerbate PFAS contamination must be evaluated under the National Environmental Policy Act (NEPA) with a rigorous analysis of cumulative impacts. The Army Corps should prepare an Environmental Impact Statement (EIS) that explicitly addresses PFAS mobilization, references the EPA’s MCLs, and incorporates the NC DEQ’s PFAS Action Plan as a baseline for mitigation. Public comment periods, informed by scientific data, are essential to ensure that the final decision balances navigational needs with the protection of public health.

Conclusion

The proposal to dredge the Cape Fear River is not merely a routine maintenance activity; it carries tangible implications for PFAS dynamics in a watershed already burdened by legacy contamination. As an environmental scientist focused on PFAS fate, I urge stakeholders to treat this project as an opportunity to apply the best available science—sediment characterization, transport modeling, and adaptive management—before any earth is moved. By aligning the Army Corps’ actions with federal MCLs, state PFAS policies, and the practical realities of municipal water treatment, we can safeguard the drinking water of hundreds of thousands of North Carolinians while still fulfilling the nation’s infrastructural obligations. The stakes are high, and the science is clear: prudent, evidence‑based decision‑making is the only path forward.