Great Lakes – St. Lawrence River Information
Water level bulletin and forecast
Monthly water level bulletin
Monthly water levels for the Great Lakes area and Montréal Harbour.
Water levels forecast
Water levels forecast for the Great Lakes.
Back issues of water levels bulletin
Browse past issues of the monthly water levels for the Great Lakes area and Montréal Harbour.
Services and information
The tide and water level gauge network
Description of and data from network of tide and water level gauges in the Great Lakes.
Great Lakes-St. Lawrence River system
Description of the lakes and channels that make up the Great Lakes-St. Lawrence River system.
Water circulation
Description of the circulation of water in the Great Lakes.
Fluctuations in water levels
Description of changes in water levels in the Great Lakes with historical charts.
Natural factors affecting water levels
How factors like precipitation and evaporation effect water levels in the Great Lakes.
Great Lakes Monthly Mean Water Level
Monthly mean water level in metres referred to chart datum.
Historical Great Lakes water level data
Historical monthly mean water levels for each of the Great Lakes from 1918 to 2016.
What we are doing
Publications
Open data
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Features
CHS Digital Transformation Initiative
At the Canadian Hydrographic Service, innovation is a guiding principle for the bold digital transformation initiative now underway.
Supporting women in hydrography
Enabling more women to participate equitably and assume more leadership roles in the field of hydrography.
2022 Tide Tables Available Now
Download your 2022 Canadian Tide and Current Tables now to help navigate safely through Canadian waters.