Monthly Water Level Bulletin

Back Issues of the Bulletin

A newsletter, LEVELnews published by Environment Canada is included with the bulletin.

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 Cleveland

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

Additional Sources of Information:

• The Great Lakes St. Lawrence River System
• Natural Factors Affecting Lake Levels
• Fluctuations in Lake Levels - types
• Circulation in the Great Lakes
• Datums - explanation of datums used for water levels and navigational charts
• US Army Corps of Engineers – Detroit District

October 2020

Great Lakes and Montreal Harbour

Monthly Bulletin prepared by the Canadian Hydrographic Service Fisheries and Oceans Canada

Water Level Advisory

Water levels for Lake Superior, Lake Michigan-Huron, Lake St. Clair, Lake Erie, Lake Ontario and Montréal Harbour are above their all-time average for this time of year and are above the level of Chart Datum.

Mariners should exercise extreme caution throughout the entire system, especially during periods of strong winds when water levels can rise or fall significantly in a short period of time.