Monitoring River Ecosystem Health

The Saskatoon H. McIvor Weir Wastewater Treatment Plant (WWTP) is a Class 4 treatment facility operating on the South Saskatchewan River (SSR) near the northeast end of the City of Saskatoon. The WWTP has undergone various upgrades since construction in 1971 to continuously improve effluent quality and meet the changing provincial and federal regulatory requirements, ultimately reducing downstream impacts on the SSR ecosystem health. An environmental risk assessment (ERA) was completed in 2015 and revised in 2017 to characterize WWTP effluent and the SSR water quality, and develop facility-specific environmental quality objectives (EQOs) and effluent discharge objectives (EDOs). 

As regulatory standards, emerging contaminants, and changing environmental conditions continue to evolve, it is crucial to conduct regular assessments to facilitate ongoing compliance and continual improvement. A river study was completed in 2019 to evaluate the effects of the WWTP effluent on the SSR ecosystem health, and make adjustments to the EQOs and EDOs to support continuous improvement of effluent treatment, and meet updated regulatory requirements.

HDR was contracted to complete an updated river study in 2024 to analyze the downstream effects of the WWTP on the SSR ecosystem health. The objective of this project was to analyze the 2020 to 2024 water quality data that was collected at upstream, effluent discharge points, and downstream locations, focusing on the typical wastewater parameters (e.g., nutrients and metals), with specific attention to nitrogen, ammonia, chloride, sulfate levels, emerging contaminants, and any other key parameters identified during the analysis. The program included collection and assessment of benthic invertebrates at upstream and downstream locations as an indicator of the river ecosystem health. 

HDR summarized the water quality data and benthic invertebrate data to identify and discuss trends and potential correlations to evaluate the WWTP’s impact on SSR water quality. This included an evaluation of the current regulatory requirements and previously established EQOs and EDOs, providing recommendations with justification for adjustments of the EQOs and EDOs for parameters of concern and for further river monitoring requirements. Emerging contaminants were also considered where adequate data was available, and where recommendations for inclusion in the future monitoring were warranted. 

Project support was provided by Musqua Environmental, wholly owned by George Gordon Developments – the business development corporation of George Gordon First Nation.