With thousands of chemicals in production and very low detection levels allowing for frequent chemical detections in our natural environment, identifying which chemicals are most likely to pose an ecological hazard is challenging. Many chemicals are present as complex mixtures for which the potential biological consequences are difficult to predict. For a sequence of Great Lakes tributary surveillance studies from 2010-2018, chemicals and chemical mixtures of ecological relevance were prioritized based on potential for biological effects. Predictions of cumulative biological effects from chemical mixtures were estimated based on summation of effects from common biological pathways. Collectively, contaminants monitored in these studies included 629 chemicals, including PAHs, flame retardants, components of plastic products, pesticides, pharmaceutical compounds, and others. With this bio-effect-based approach, the number of chemicals targeted for further consideration was reduced by about 90% (to 65 chemicals) from the original list of chemicals analyzed, allowing resource managers to focus on chemicals with the greatest potential for adverse ecological effects.