Effects of centralized and onsite wastewater treatment on the occurrence of traditional and emerging contaminants in streams.

: The authors conducted a survey of small streams to evaluate the effects of centralized and onsite wastewater treatment on the occurrence of selected traditional and emerging contaminants in small streams in the upper Neuse River basin, North Carolina. An undeveloped site was included to assess effects of residential land use activities on stream quality. Concentrations of nutrients and ions were higher in samples from streams in residential sites than from the stream in an undeveloped area. Overall, streams draining residential areas showed relatively small differences with respect to type of wastewater treatment. Two sites, however--one in an area of centralized wastewater treatment apparently near a suspected sewer line leak, and the second in an area of onsite wastewater treatment--showed effects of wastewater. Organic wastewater compounds were detected more frequently in samples from these two sites than from the other sites. Optical brighteners levels were correlated (r2 = .88) with the number of organic wastewater and pharmaceutical compounds detected at the residential sites and could potentially serve as a screening method to assess wastewater effects on small streams.