Panel (a): surface water from watersheds with an AFFF source zone (blue, n = 41) and without an AFFF source (orange, n = 13). Panel (b): Literature data on fluorotelomer (FT) AFFF (purple, n = 19, manufactured between 1986–2017), electrochemical fluorination (ECF) AFFF (green, n = 9, manufactured between 1988–2001), and AFFF impacted surface water from this study (blue, n = 41). Circles in panels (a) and (b) represent the minimum convex hull that encircles all data within the group.