Toxic Threats Revealed In Delaware Estuary Tributaries: New DRBC Report Flags Widespread Pollution

A newly released report by the Delaware River Basin Commission (DRBC) reveals alarming levels of both legacy and emerging contaminants in the tributaries feeding the Delaware estuary, one of the nation’s most vital and industrially active waterways. Conducted in fall 2023 and published in April 2025, the study sampled water from 12 tributaries across Pennsylvania, New Jersey and Delaware, uncovering a complex mix of hazardous substances, including polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFAS), dioxins, furans, banned insecticides and modern agricultural chemicals.

According to the report, every sampled tributary exceeded DRBC and EPA water quality criteria for PCBs once commonly used in electrical equipment and banned since the 1970s but still found in alarming quantities, with Marcus Hook Creek showing the highest levels. PFAS, often dubbed “forever chemicals,” were also detected at every site, with PFOA and PFOS concentrations surpassing proposed human health thresholds across the board. The Christina river in Delaware emerged as a pollution hotspot, recording the highest PFAS levels and ranking among the most contaminated for PCBs, PAHs and dioxins.

Even banned insecticides like DDT and dieldrin remain stubbornly present decades after prohibition. Frankford creek in Philadelphia stood out with the highest concentrations of both legacy and current-use insecticides, including neonicotinoids and pyrazoles, suggesting ongoing usage in the surrounding landscape. Meanwhile, Mantua creek in New Jersey topped the charts for polycyclic aromatic hydrocarbons (PAHs), compounds linked to fossil fuel combustion.

“These findings highlight a troubling blend of old and new chemical threats,” said DRBC’s lead scientist Dr. Jeremy Conkle. “Despite regulatory bans, persistent pollutants like PCBs and dieldrin remain widespread, while new contaminants like PFAS and neonicotinoids are on the rise.”

Funded through the Bipartisan Infrastructure Law via the Partnership for the Delaware Estuary, the project aims to close longstanding data gaps, support regulatory action and protect drinking water, ecosystems and public health. The DRBC warns that the presence of these chemicals, many of which bioaccumulate, poses a continued risk to aquatic life and communities that rely on the river for recreation and sustenance.

The report offers a crucial wake-up call for coordinated efforts to reduce pollutant loads, remediate contaminated sites, and set stringent criteria for emerging contaminants. As the region balances industrial heritage with environmental sustainability, the health of the Delaware Estuary may well depend on how swiftly these insights are turned into action.