Historical Monthly and Yearly Mean Water Level 1918-2020

Historical Water Level DataHistorical monthly mean water levels from the coordinated network of gauging stations for each of the Great Lakes.

  • A tabular representation of the Historical Monthly Mean Water Levels

Computed from Coordinated Network Mean Water Levels

A network of gauging stations on both sides of the border on each lake is used to determine the average water level for the month. The following stations are used:

Lake Superior at:  Thunder Bay, Michipicoten, Duluth, Marquette and Point Iroquois 

Lakes Michigan/Huron at:  Thessalon, Tobermory, Milwaukee, Ludington, Mackinaw City and Harbor Beach  

Lake St. Clair at:  Belle River and St. Clair Shores

Lake Erie at:  Port Stanley, Port Colborne, Toledo and Fairport 

Lake Ontario at:  Port Weller, Toronto, Cobourg, Kingston, Rochester and Oswego