Trends in Hamilton Harbour suspended sediment quality

Suspended sediment quality in Hamilton Harbour has been assessed as part of a long-term monitoring study (1987-2012). Sampling locations reflected a range of shoreline activities and sources of chemical contamination to the harbour. Temporal data showed a trend toward decreasing levels of contamination by polycyclic aromatic hydrocarbons and polychlorinated biphenyls over the period from the late 1980s to the early 1990s, with a subsequent leveling off over the next two decades. The highest concentrations of both contaminants were detected in areas impacted by industrial activities along the southern shoreline and Windermere Arm, and deep-water areas of the harbour where fine-grained sediments ultimately accumulate. Areas of the harbor discharging residential or rural parts of the watershed exhibited generally lower levels of contamination. In addition to the relatively higher contaminant levels, areas along the southern shoreline and Windermere Arm characterized by historical industrial activities and associated contaminated sediments exhibited chemical profiles indicating an impact on suspended sediment and bottom sediment quality throughout the harbour. Continued monitoring after scheduled remedial activities should provide an assessment of the overall efficacy of management actions to improve sediment quality in Hamilton Harbour.