Study uses sediment and stonefly larvae at 66 sites, targets all 209 PCB congeners

Hill said the team deliberately chose two relatively immobile matrices — surface sediment and macroinvertebrates (stonefly larvae) — to reduce the spatial mobility that can confound fish‑tissue interpretations. He described field tactics (riffle selection, overturning rocks, kick nets) and said stoneflies were collected at every site, allowing consistent paired analyses.

"These were randomly selected locations that used the same methods as EPA's National Rivers and Streams assessment," Hill said, noting the final analytical method (1668C) measures all 209 congeners and also reports lipid content to help interpret organism concentrations.