Pesticides and PCB residues in the Black Creek Watershed, Allen County, Indiana--1977-78.

The aquatic environment of a small agricultural drainage in northeastern Indiana was surveyed during 1977-78 for pesticide and PCB contamination. A total of 45 water, sediment, and fish samples from Black Creek watershed, Allen County, Indiana were analyzed for seven pesticides and PCBs. Low levels of dieldrin (mean 0.023 micrograms/g) and DDE (mean 0.016 micrograms/g) were found in all fish samples, but were not detected in water or sediment samples. PCB concentrations in fish were five times greater (0.102 micrograms/g) than were organochlorine pesticide concentrations. Two of seven water samples contained PCBs at 0.4 micrograms/liter and 0.2 micrograms/liter. Only the herbicide 2,4,5-T occurred in surface water samples during low stream discharge, at concentrations of 0.2--7.7 micrograms/liter. Atrazine, alachlor, carbofuran, and malathion were not detected in any samples.