Abstract

Environment Canada has conducted a water quality Surveillance Program on Lake Ontario since the late 1960s. Recent literature and discussion about water quality in the Great Lakes has focused on toxic organic compounds. In this presentation, the focus will instead be on “conventional” water quality parameters such as nutrients (e.g., phosphorus, nitrogen) and major ions (e.g., calcium, chloride). For some of these compounds, temporal trends of 30 to 40 years are available. A focus will be placed on changes occurring in the past 15 years, some of which are likely attributable to the introduction of zebra mussels to Lake Ontario in 1990.