Assessing effects of industrial effluent on wetlands surrounding a wastewater treatment facility using a multiple lines of evidence approach

Abstract

A former estuary, known as the Boat Harbour Treatment Facility (BHTF), has been used to treat industrial effluent since 1967. This effluent created large volumes of unconsolidated sediment impacted by inorganic and organic contaminants. The BHTF will no longer be used after January 2020 under the Boat Harbour Act (2015), with remediation commencing thereafter. This study builds on prior assessments by evaluating potential effects on wetland biological communities surrounding the BHTF through completion of contaminant and macroinvertebrate community analyses. Sediment, surface water and biota samples were analyzed for contaminants of potential concern. Results were compared to provincial/federal guidelines and reference wetlands, and revealed several exceedances in wetland media. Macroinvertebrate community analysis was based on the ECCC Wetland CABIN protocol. Community metrics in BHTF wetlands showed little variation from reference wetlands. Recommendations for remediation include active remediation in impacted sediments and passive remediation in less impacted wetlands using monitored natural recovery.