Wastewater reuse and predicted ecological risk posed by contaminant mixtures in Potomac River watershed streams

• Published in: Journal of the American Water Resources Association Vol. 59; no. 4; pp. 779 - 802
• Main Authors: Faunce, Kaycee E., Barber, Larry B., Keefe, Steffanie H., Jasmann, Jeramy R., Rapp, Jennifer L.
• Format: Journal Article
• Language: English
• Published: Middleburg Blackwell Publishing Ltd 01.08.2023
• Subjects: Aquatic organisms; Contaminants; Creeks & streams; Dilution; Drinking water; Effluents; Environmental degradation; Environmental risk; Fish; Mixtures; Municipal wastewater; predicted environmental concentrations; Risk assessment; river water; Rivers; Stream order; Streams; Wastewater; Wastewater discharges; Wastewater pollution; Wastewater reuse; Water intakes; water resources management; Water reuse; Watersheds; Potomac River
• ISSN: 1093-474X; 1752-1688
• DOI: 10.1111/1752-1688.13110

A wastewater model was applied to the Potomac River watershed to provide (i) a means to identify streams with a high likelihood of carrying elevated effluent‐derived contaminants and (ii) risk assessments to aquatic life and drinking water. The model linked effluent discharges along stream networks, accumulated wastewater, and predicted contaminant loads of municipal wastewater constituents while accounting for instream dilution and attenuation. Simulations using 2016 data suggested that nearly 30% (8281 km) of streams were wastewater impacted. Low‐ to medium‐order streams had the largest range of accumulated wastewater (ACCWW%) values. ACCWW% exceeded a 1% threshold at >39% of drinking‐water intakes (varied by temporal condition). Risk assessments of municipal wastewater‐contaminant mixtures indicated that 22% (1479 km) of streams impacted by municipal wastewater (5.5% of all reaches modeled) may pose high risk to aquatic organisms under mean‐annual conditions, with fish more susceptible to chronic‐exposure effects relative to other taxa. Risk varied temporally and by stream order, with the greatest risk occurring in the summer in small streams. These findings suggest that wastewater may be an important factor contributing to environmental degradation in the Potomac River watershed.