PFAS and other toxic contaminants can enter surface water through overland flow, such as stormwater runoff, through industrial discharges, through atmospheric deposition and through discharge of contaminated groundwater.

Once in the surface water, contaminants can contribute toxicity to fish and other aquatic life. Some contaminants may also be taken up by local fish and other aquatic life in the process of bioaccumulation.

This not only increases the body burden of the chemicals in the fish themselves, potentially causing impacts, but it also creates an exposure pathway to higher life forms like birds who feed on fish (such as kingfishers, great blue heron, osprey, bald eagles), aquatic mammals like otters and humans through the consumption of contaminated fish.

Statewide Surface Water Studies

Initial Comprehensive Study

DNREC’s Watershed Approach to Toxics Assessment and Restoration (WATAR) team conducted a comprehensive statewide PFAS surface water study in the fall of 2022 to document the nature, extent, magnitude and distribution of PFAS contamination in surface waters across the state.

This initial survey contributed to Delaware’s understanding of the overall distribution of PFAS in environmental media. The data also provided important forensic clues, or lines of evidence, regarding sources of PFAS in Delaware watersheds.

Data Summary Report

PFAS in Delaware Surface Waters: Data Summary Report (2024)

• Appendix A: PFAS Data Tables
• Appendix B: PFAS Data Plots
• Appendix C: Laboratory Analytical Report and EXCEL Data File

Follow-up Studies and Statewide Monitoring

While follow-up actions and additional investigations are occurring in specific watersheds based upon the initial surface water sampling results, DNREC aims to continue monitoring PFAS in surface water on a broad scale.

The continued collection of data will aid in the detection of new PFAS sources, the documentation of changes to known PFAS sources and in establishing long term trend information.

A newly updated Quality Assurance Project Plan (QAPP) Surface Water Sampling II has been prepared and sampling was scheduled to take place in the fall of 2026. Results of the statewide surface water sampling event will be made available to the public by Summer 2027.

Continued Caution Recommended

DNREC recommends that the public be aware of PFAS concentrations in the waters that they frequent. The science surrounding PFAS exposure is ever advancing and, as DNREC continues to learn and share information about PFAS in Delaware’s environment, understanding how to limit personal exposure to PFAS is critical.

Related Topics:  EPA, GenX, HSCA, PFAS, PFOA, surface water, waste and hazardous substances, watar, water