Toxic Contaminants Research

Recent Progress: Increase

Through collaboration with stakeholders and the incorporation of local Total Maximum Daily Load pollutant limits into stormwater permits, the Toxic Contaminants Workgroup has made progress in addressing the impacts of mercury across the watershed and other contaminants of interest in local areas. Regional characterizations improved for agricultural chemicals in the Potomac and Susquehanna watersheds, for PCBs related to restoration efforts in the Anacostia watershed, and for complex mixtures of contaminants in the Shenandoah watershed. The workgroup has also improved our understanding of the reduction of specific contaminants in response to some management actions, but further progress will require additional pollutant removal efficiency studies for stormwater best management practices.

Outlook: Off Course

The Toxic Contaminants Research Outcome is off course. This outcome encompasses research of many toxic contaminants and lacks specific measures of progress, which poses challenges for making the science actionable. We hope to overcome these challenges through cross-workgroup collaboration. Despite the progress made on characterizing the occurrence, concentrations, sources and effects of mercury, PCBs, and polyfluoroalkyl substances (PFAS), our ability to characterize more regional occurrences and concentrations of other contaminants, such as pesticides, has been limited. We need to identify an appropriate method to link toxic contaminant science to stakeholder tools to achieve co-benefits between nutrient, sediment and contaminant reductions.

Research Issues Status

The Toxic Contaminants Workgroup’s baseline understanding of each of the issues its research agenda should address differs and are as follows:

Issue: Supplying information related to the safe consumption of fish and shellfish.

• Most of the fish consumption advisories issued in the watershed are caused by polychlorinated biphenyls (PCBs) and/or mercury. These pollutants can come from legacy deposits, ongoing inputs and ongoing releases. Work related to the Toxic Contaminants Policy and Prevention outcome will address PCBs, while recently passed air emission controls will address mercury.

Issue: Understanding the influence of contaminants degrading the health and contributing to the mortality of fish and wildlife.

• Research strongly suggests the influence of toxic contaminants on numerous indicators of reduced fish health (e.g., skin and liver tumors, intersex and other gonadal abnormalities, high parasite loads and opportunistic infectious diseases) and occurrences of fish kills throughout the watershed. The role of contaminants in the health of birds, reptiles and amphibians is not as well documented. There is less evidence linking contaminants to the reduced health of underwater grasses, stream invertebrates and other lower trophic level organisms.

Issue: Documenting the sources, occurrence and concentrations of contaminants harming fish and shellfish.

• A technical report shows PCBs and mercury are particularly problematic in the region, and are considered widespread in severity and extent. Polycyclic aromatic hydrocarbons (PAHs) and some herbicides are also considered widespread in extent, while dioxins, petroleum hydrocarbons, some chlorinated insecticides and some metals occur locally. Information is insufficient to determine the extent of biogenic hormones, household and personal care products, pharmaceuticals or flame retardants.

Issue: Assessing the relative risk of contaminants harming fish and shellfish and the mitigation options that could inform policies for their prevention.

• There is no organized information on the relative risk of different contaminant groups. However, because PCBs and mercury are widespread in extent and severity, PCBs will be the focus of the Toxic Contaminants Policy and Prevention outcome. Mercury will likely be the next pollutant addressed.

Issue: Gathering information on issues of emerging concern.

• Issues of emerging concern include contaminant toxicity to pollinators, microplastics and the unconventional drilling of oil and gas known as “fracking.” The baseline information on each of these is limited.

Learn About Factors Influencing Progress

To achieve this outcome, Chesapeake Bay Program partners have committed to:

• Supplying information related to the safe consumption of fish and shellfish;
• Understanding the influence of contaminants degrading the health and contributing to the mortality of fish and wildlife;
• Documenting the sources, occurrence and transport of contaminants in different landscapes;
• Providing science to help mitigate contaminants and emphasize the co-benefits of nutrient and sediment reductions; and
• Gathering information on issues of emerging concern.

Monitoring and assessing progress toward the outcome will occur through a range of environmental indicators, including the occurrence of mercury, PCBs and other toxic contaminants and the number and location of fish health consumption advisories.

As part of the Chesapeake Bay Program’s partnership-wide implementation of adaptive management, progress toward this outcome was reviewed and discussed by the Management Board in September of 2022. It will be reviewed and discussed by the Management Board again in August of 2024.

Download Management Strategy (.pdf)

Chesapeake Bay Program partners have committed to taking a series of specific actions that will support the management approaches listed above.

Learn About Logic & Action Plan

The Water Quality Goal Implementation Team leads the effort to achieve this outcome.

Participating partners include:

• Delaware Department of Natural Resources and Environmental Control (State of Delaware)
• Maryland Department of the Environment (State of Maryland)
• Maryland Department of Natural Resources (State of Maryland)
• University of Maryland, Baltimore County (State of Maryland)
• New York Department of Environmental Conservation (State of New York)
• Pennsylvania Department of Environmental Protection (Commonwealth of Pennsylvania)
• Virginia Department of Environmental Quality (Commonwealth of Virginia)
• Virginia Institute of Marine Science (Commonwealth of Virginia)
• Virginia Polytechnic Institute and State University (Commonwealth of Virginia)
• West Virginia Department of Environmental Protection (State of West Virginia)
• Department of Energy and Environment (District of Columbia)
• Chesapeake Bay Commission
• National Oceanic and Atmospheric Administration
• U.S. Department of Homeland Security
• U.S. Environmental Protection Agency
• U.S. Fish and Wildlife Service
• U.S. Geological Survey
• Bluewater Baltimore
• Maryland Pesticide Network
• Metropolitan Washington Council of Governments