Current and Forecast Lake Ontario Water Level Information

The federal government and International Lake Ontario – St. Lawrence River Board (ILOSLRB) monitors Lake Ontario levels and provides forecasts for future conditions. This information is available at:

Water Level Conditions & Marine Forecasts

Lake Ontario St. Lawrence River Board

Factors that Influence Lake Ontario Water Levels

There are three types of water level fluctuations – long-term, seasonal, short-period, and wind generated waves. These fluctuations are explained at There are also natural factors that affect water levels, they are also explained at Cataraqui Conservation Authority does not control Lake Ontario water levels.

Video – Causes of 2017 Lake Ontario – St. Lawrence River Flood – Produced by the International Joint Commission. Recap of 2017 conditions and explanation of how water levels are managed on Lake Ontario and the St. Lawrence River.