Water-Quality Assessment of part of the Upper Mississippi River Basin, Minnesota and Wisconsin— Organochlorine compounds in streambed sediment and fish tissues, 1995-97

Streambed sediments and fish tissues were collected in part of the Upper Mississippi River Basin to assess the presence and distribution of organochlorine compounds (OCs) including PCBs. A total of 13 OCs were detected among 14 of 27 streambed sediment sampling locations. In fish tissues analyzed, 9 OCs were detected among 17 of 24 sites sampled. Eight OCs were detected in both fish and streambed sediment samples, they were: cis-chlordane, o,p'-DDD; p,p'-DDD; p,p'-DDE; p,p'-DDT; hexachlorobenzene; transnonachlor; and PCBs. The most frequently detected OCs were: p,p'-DDE; and p,p'-DDD in streambed sediment and p,p'-DDE and PCBs in fish tissues. No OCs were detected in streambed sediment at agricultural sites; however, the agricultural sites had 17 detections of OCs in fish tissue. Urban streams had concentrations of total DDT and metabolites in streambed sediment that exceed guidelines for classification of sites with high probabilities of adverse effects to aquatic organisms. Total DDT was the only OC within an urban land use that exceeded guidelines for piscivorous wildlife.