A sensitive bioassay, based on EROD induction in cultured chicken embryo livers, was used together with chemical analysis to determine levels of dioxin-like contaminants in particulate matter in Eman. Extracts of sediment and settling particulate matter (SPM) collected in the river system before, during, and after dredging of a PCB contaminated lake, Lake Jarnsjon, were separated into three fractions containing a) monoaromatic/aliphatic; b) diaromatic (e.g., PCBs and polychlorinated dibenzodioxins and dibenzofurans); and c) polyaromatic compounds (e.g., polycyclic aromatic hydrocarbons). The samples from Lake Jarnsjon contained the highest PCB concentrations and the diaromatic extracts from Lake Jarnsjon samples showed the highest activities of EROD-inducing diaromatic compounds. The dioxin-like activity of the diaromatic fraction in sediment collected after the dredging of Jarnsjon had only around 1% of the activity of the pre-dredging sediment, showing that the remediation was successful in terms of removal of the PCB-contaminated sediment from the lake. In SPM collected immediately downstream from Jarnsjon, levels of diaromatic dioxin-like compounds were elevated during the dredging, and decreased after that. The post-dredging concentrations were however higher than in SPM from lakes upstream of Jarnsjon, showing that elevated levels of dioxin-like diaromatic compounds were still present in the water System downstream of Jarnsjon a couple of years after the dredging.