Fisheries and Oceans Canada * Pêches et Océans Canada Canada
Français CHS HQ Water Levels Canada Site
CHS crest       The Canadian Hydrographic Service
      Central and Arctic Region

Monthly Water Level 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          

Water Levels / Niveaux d'eau . PDF

Water Level Bulletin PDF file

A copy of the latest edition of the bulletin Water Levels Great Lakes and Montreal Harbour in Portable Document Format (pdf).  To view this document you require Adobe Acrobat Reader.  To obtain a free copy of the software, click on the following icon.


 Back Issues of the Bulletin

Copies of  back issues of the Bulletin Water Levels Great Lakes and Montreal Harbour

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

Link to

Great Lakes and Montreal Harbour

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

Grands Lacs et port de Montréal

Bulletin mensuel préparé par le
Service hydrographique du Canada
Ministère des Pêches et des Océans

October 2014 Octobre

Water Level Advisory  

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



Monthly Mean Water Levels
in metres referred to IGLD 1985
Niveau d'eau moyen mensuels
en metres par rapport au SRIGL 1985
October   2014   Octobre Superior
Huron St. Clair
Ontario Montréal
Mean for Month (preliminary data)
Moyenne mensuelle (données préliminaires)
183.71 176.54 175.18 174.25 74.59 6.13
Mean for month last year
Moyenne mensuelle, l'année dernière
183.45 176.01 174.85 174.07 74.64 5.68
Mean for month, last 10 years
Moyenne mensuelle, 10 dernières années
183.28 176.03 174.84 174.04 74.59 5.95
Statistics for period of record
Statistiques pour la periode d'observation
1918-2013 1918-2013 1918-2013 1918-2013 1918-2013 1967-2013
Maximum monthly mean / year
Moyenne mensuelle maximale / année
Mean for month / Moyenne mensuelle 183.50 176.43 174.98 174.06 74.61 6.27
Minimum monthly mean / year
Moyenne mensuelle minimale / année
Probable mean for next month
Moyenne probable du mois prochain
183.66 176.53 175.10 174.16 74.48 6.13
Chart Datum  /  Zéro des cartes 183.2 176.0 174.4 173.5 74.2 5.55


The monthly mean levels for the previous year and current year shown on the graphs are the average of water levels recorded at a network of gauging stations on each lake.  Historical data from these networks are used to determine the all-time average and the historical extreme monthly levels.

Water levels for the Canadian stations in the networks are collected by the Canadian Hydrographic Service.  Six month forecasts of the probable range of future levels are prepared under the auspices of the International Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data by Environment Canada and the Detroit District, Corps of Engineers.

This bulletin is prepared each month as a public service and is available on the World Wide Web at:

Additional information on water levels in the Great Lakes System may be obtained by telephoning the Canadian Hydrographic Service at (877) CHS-LINK (877-247-5465), by fax at (905) 336-8916, or by email at


Last Updated: 11/05/2014

Important Notices

Previous Page

Français | Canada Site
  Water Levels | CHS HQ