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Evaluating land use impacts on contaminants of emerging concern in Cape Cod Bay estuaries

Funding for this project was provided by MassBays to Center for Coastal Studies (2016)

About the project

Research by Silent Spring Institute (SSI) has documented the presence of contaminants of emerging concern (CECs) in septic systems, groundwater, ponds, and  drinking water wells throughout Cape Cod. The most frequently detected types of chemicals include: prescription medications, organophosphate flame retardants, per- and polyfluoroalkyl substances, and an artificial sweetener, acesulfame. Ponds and drinking water wells with higher nitrate levels and more extensive proximal land development (both indicators of septic system impact) had higher levels of CECs. A recent synthesis of studies on CECs in septic systems showed that while septic systems effectively remove come CEC’s in household and commercial wastewater, substantial amounts may be released into watersheds that supply Cape Cod estuaries, particularly in densely developed areas.

Building on SSI’s work, and with funding from MassBays in 2012, the Center for Coastal Studies (CCS) tested for and provided the first documentation of the presence of CEC’s in Massachusetts coastal waters. A second grant in 2016 allowed CCS to conduct the most extensive assessment of CEC’s in Cape Cod Bay estuaries, and evaluate causal relationships between land use activity and the extent of CEC contamination.

10 sites within 8 embayments in Cape Cod Bay were selected for the survey (see map below). Details of the methods used are described in the report: Evaluating land use impacts on contaminants of emerging concern in Cape Cod Bay Estuaries. Costa et al. 2017.

map of sites

During this study, CECs were commonly detected in tidal creeks impacted by septic systems. While the concentrations measured in this study are below ecotoxicological thresholds, the presence of mixtures of these xenobiotic compounds do raise concerns about potential ecotoxicological effects.


Results indicated a correlation between dissolved inorganic nitrogen concentrations and the presence of CECs. This finding corroborates similar findings in Cape Cod drinking water wells and ponds. As Cape Cod communities develop wastewater management plans to address nutrient pollution in surface water bodies, it is important to consider the presence of CECs in nutrient-rich groundwater and the potential for CEC bioaccumulation and ecological impacts in areas most affected by septic system pollution.

Building on the findings of this study, future work will further refine land use analyses to more accurately delineate the areas that are most likely to contribute to the water quality at these sampling locations. Based on the results additional studies at specific sites will help provide information on possible non-wastewater sources that need to be addressed.

Overall, the information gathered from this study will provide MassBays with an assessment of ecological health risks and provide a more complete understanding of how land use patterns affect water quality.

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