Cumulative impacts on water

Update, September 2016 – As part of FOCA’s commitment to watershed health, we are interested in the effects of cumulative impacts. Cumulative effects are incremental and accumulating changes to the environment which are caused by both natural (e.g., seasonal cycles) and man-made disturbances (e.g. development activities).

Cumulative Effects Assessment (CEA) is the process of monitoring, tracking and predicting accumulating environmental change relative to established limits. Historically in Canada, CEA was conducted through federal and provincial Environmental Impact Assessment processes by industry proponents applying for approval for a project development. However, the methodology for CEA has thus far failed to produce the intended outcomes of monitoring, tracking and ultimately predicting accumulating environmental change.

Unfortunately today in Canada, CEA is fragmented by jurisdictional responsibilities and siloed expertise. This fragmentation has reduced our ability to understand the state of our environment and critical changes due to human activities.  Our ability to predict what may occur in the future is limited.

According to recent research headed by Dr. Monique Dubé at the University of New Brunswick, no one has successfully packaged the pieces of CEA into an effective process. Monitoring, tracking and predicting cumulative effects of multiple natural and man-made influences on environmental components (i.e., air, land, water, and biodiversity) over space and time requires the integration of many complex pieces of information.

Fortunately, thanks to the long-term and broad geographic sampling efforts of Lake Partner Program volunteers, in Ontario there is a growing database of environmental indicators that can help support this complex decision-making in the future. This data is already being used to produce a geospatial database that describes land-based predictors of multiple stressors from the catchment for thousands of Ontario’s inland lakes. This project was undertaken with the support of the Melles Lab at Ryerson University, and provides FOCA member groups with a way to visualize and assess their lake’s water quality in relation to other lakes in the Province. See more about the multiple stressors project here.


Another Canadian Water Network project featured a research team consisting of scientists from seven universities and the Ontario Ministry of Environment and Climate Change who conducted 11 unique studies, using data collected over three years and historical data from more than three decades of monitoring. The studies:

  • Described the chemical, climatic and biological conditions within watersheds, and identified indicators of stressors, biological effects and aquatic ecosystem condition.
  • Grouped lakes according to natural habitat type and stressor exposures to determine which groups should be monitored and modelled.
  • Examined the mechanisms that underlie the ecosystem responses occurring in the Muskoka River Watershed, to facilitate predictive modeling and selection of indicators relevant to the cumulative effects monitoring program.
  • Developed modelling tools that associate stressors and cumulative effects to predict and forecast watershed processes, chemical state and biological condition, and facilitate monitoring of cumulative effects.

The Cumulative Effects work showed that, across the Muskoka landscape the major stressors influencing waterways include acid rain, climatic variability, shoreline development, land-use change and invasive species. Other potentially relevant stressors not addressed in this project include contaminants from pharmaceuticals and personal care products, and dam construction for energy production.

The findings from this project were integrated with previous research completed in the Muskoka River Watershed to develop a better understanding of how stressors are linked to cumulative effects, and how these may directly and indirectly impact freshwater services.

FOCA applauds the ongoing work of our scientific and citizen science partners in support of these efforts!

Terry ReesCumulative impacts on water