Areas of Concern (AOCs) are geographic areas within the Great Lakes basin, identified in the mid-1980s, where significant impairment of beneficial uses of the environment has occurred resulting from localized human activities. Water quality and ecosystem health monitoring and surveillance is conducted to assess ecosystem impairment in Areas of Concern (AOCs) and to track the effectiveness of remedial actions aimed at restoring beneficial uses. Remediating AOCs contributes to the sustainability of local communities and of the Great Lakes region, and is a joint commitment under the Canada-United States Great Lakes Water Quality Agreement (GLWQA). This dataset contains data collected by the Water Quality Monitoring and Surveillance Division of Environment and Climate Change Canada used in these assessments.