Forage Fish Polychlorinated Biphenyl Monitoring to Support Sediment Cleanup and Source Control in the Anacostia River Watershed, Washington, DC and Maryland, USA

<title>Abstract</title> <p> Game fish can bioaccumulate polychlorinated biphenyls (PCBs) from sediments, diet, and water to concentrations requiring the issuance of Fish Consumption Advisories. To reduce impacts, sediment PCB cleanups are often conducted in phases using adaptive management (early action, performance monitoring, and remedy review). Abundant forage fish with high-site fidelity and short lifespans are useful for monitoring focused on the critical food chain pathway for human exposure. In this study, PCBs were monitored in whole-body mummichog ( <italic>Fundulus heteroclitus</italic> ) and banded killifish ( <italic>F. diaphanus</italic> ) throughout the Anacostia River and tributaries in Washington, DC and Maryland, USA. Our goal was to evaluate biological, chemical, logistical, and statistical issues for effective and cost-efficient monitoring. The objectives were to: 1) compare total PCBs across locations, focusing on Lower Beaverdam Creek (LB), known to have the highest tributary PCB loading; 2) interpret patterns in homologs; and 3) provide monitoring recommendations. From 2018 through 2022, we collected 2148 fish (185 composite samples) at 22 locations. Of the tributaries, fish from LB had the highest total PCBs (313 parts per billion (ppb) to 2500 ppb), with Northwest and Northeast Branches lowest at 30.2 ppb to 95.8 ppb. LB fish had the highest percentages of lower chlorinated homologs, indicating recent or current releases. Elevated PCBs in the tidal Anacostia below the mouth of LB added to the weight of evidence implicating LB as a major source of loading. Linear models identified lipid as a significant covariate. Recommendations on analytical methods, sampling strategy, reference locations, seasonality and scheduling were provided. </p>