PCB Mass Loading Studies

The DNREC Division of Waste and Hazardous Substances and Division of Watershed Stewardship are working together to study polychlorinated biphenyls (PCBs) and how they enter surface waters from hazardous substance release sites around the state.

The studies are led by the Remediation Section in Waste and Hazardous Substances, and the Watershed Assessment and Management Section in Watershed Stewardship as part of the department’s Watershed Approach to Toxics Assessment and Restoration (WATAR).

Phase I of the study focused on PCB mass loading from hazardous substance release sites to surface waters of the Christina River basin. Phase I was completed in 2009.

Phase II, completed in 2015, focused on PCB mass loading from hazardous substance release sites to waters across the rest of the state.

About PCBs

PCBs are hazardous man-made industrial chemicals that are no longer manufactured in the U.S., but are nevertheless widespread in the environment as a result of past usage, poor disposal practices, and their slow breakdown. These studies compiled information on the presence and levels of PCBs at hazardous substances sites across the state and then estimated how PCBs at these sites continue to be released to nearby surface waters.

Although the presence of PCBs can pose a potential risk to people and wildlife that visit hazardous substances sites, the release of PCBs can result in especially high risks when these chemicals enter adjacent surface waters and bioaccumulate in fish and other aquatic life.

Bioaccumulation is the process where a chemical builds up in fish to levels far greater than in the water itself. Once PCBs are in the fish, people who regularly eat the fish are at greater risk of various adverse health effects. In addition, birds that consume fish – such as ospreys, bald eagles, and herons – as well as other fish-eating animals such as otters are also at risk when they consume fish containing PCBs.

Learn more about fish consumption advisories in Delaware.

The DNREC collaborative study is a critical step in a much larger project that aims to link upland sources of PCBs with their primary impact in surrounding waterways. Because this project considers all sites known to be contaminated to one degree or another with PCBs, the information gathered will allow DNREC to look at the cumulative impact of PCBs in the area. This brings a new and more holistic perspective to the problem, which in turn could lead to innovative management solutions. DNREC refers to this holistic approach as the Watershed Approach to Toxics Assessment and Restoration (WATAR).