Analysis, Evaluation, and Reporting of Environmental Monitoring Data for the Lower Athabasca River

This report presents the findings of an enhanced monitoring study on baseline environmental conditions in the Lower Athabasca River (LAR), conducted under a project designed by the Oil Sands Process Water - Science Team (OSPW-ST) in 2018. Funded by the Oil Sands Monitoring Program (OSMP) and led by EPA from 2018 to 2023. A primary objective of this research was to inform future Environmental Effects Monitoring (EEM) study designs related to the potential future release of treated tailings water in the Alberta Oil Sands Region. The report estimates normal ranges for key monitoring endpoints, including surface water and sediment quality, algae, benthic invertebrates, and sentinel fish populations and fish communities. Using predictive models, the study identifies sources of variation, recommended sample sizes (power analysis), and thresholds (triggers) to support the design of an effective EEM program. A recommended approach for establishing normal ranges using general linear models is also provided, accounting for variability across environmental factors. A key finding indicates that river discharge is the most significant driver of variation in water quality, sediments, algae, invertebrates, and fish populations. Once discharge is controlled, temporal and spatial variability is minimal across LAR monitoring sites. The findings of this study, including baseline environmental data, methods for estimating normal ranges to develop triggers, and EEM study design guidance, provide valuable insights for government agencies, stakeholders, and policymakers. This report can help inform regulatory decisions regarding potential point-source releases of treated oil sands process water (OSPW) in the oil sands region.