Great Lakes Environmental Assessment and Mapping Project

Our Approach

The Great Lakes Environmental Assessment and Mapping Project (GLEAM) evaluates multiple stressors affecting the Great Lakes ecosystem. GLEAM merges spatial data layers representing all major categories of stressors to the Great Lakes, ranging from climate change and land-based pollution to invasive species, into a single map of cumulative stress. The synthesis of this information into a single map enhances our ability to manage and restore the Great Lakes ecosystem. The final map can be used to assess stressor impacts at locations with significant human benefits and to evaluate conservation and restoration opportunities.


Why maps?

  • Maps of valued resources and potential threats provide a critical starting point for evaluating conservation and restoration opportunities.
  • All management efforts are tied to specific places.
  • Knowing the spatial distribution of stressors and human benefits will help guide the effective management of Great Lakes resources.



The GLEAM project included four main steps.  First, we mapped the intensity of stressors across the Great Lakes (1 km2 resolution).  The project team obtained or generated data to map 34 of the 50 stressors our core working group originally identified as potentially mappable and currently impacting the Great Lakes. Second, we developed weightings of relative impact of each stressor by habitat type, based on a survey of Great Lakes experts.  Third, we derived a cumulative stress (CS) map by summing all of the stressors - see this map on our home page.  Finally, we identified and mapped areas that provide highly valued recreational, biological, and economic opportunities.  Spatial data sources and mapping methods are described on individual stressor pages and human benefits pages, and details about calculations and analyses can be found in the scientific publication (coming soon!).

CS intensity example