LEVELnews: Great Lakes and St. Lawrence River water levels, February 2023

All the Great Lakes experienced very wet conditions during January

During January, the Great Lakes Basin experienced the following:

• The mean monthly water levels of all the Great Lakes were above average.
• All the Great Lakes experienced water supply conditions (a combination of the precipitation, evaporation, and runoff), that were well above average, with Lake Ontario recording its fifth wettest January on record.
• Lake Superior experienced less than average precipitation, Lake Michigan-Huron was close to average, while Lakes Erie and Ontario received higher than average precipitation.  The evaporation from the lakes was less than average and the runoff into the lakes was close to average for all the lakes but Lake Ontario, which had much higher than average incoming runoff from rainfall and snowmelt.
• Lakes Superior and Michigan-Huron experienced below average water level declines for January. Both Lake Erie and Lake Ontario rose much more than usual.

Relative to their beginning-of-February levels and with average water supplies for this time of year, Lake Superior is expected to continue its seasonal decline into late winter, while the other lakes are expected to begin the transition from their seasonal decline to their seasonal rise in the coming months.

With water levels remaining above average in all lakes, and the possibility of large storms and winds, low-lying areas are at risk for accelerated coastline erosion and flooding. For current information and forecasts, please refer to the sources listed below.

We have updated the LEVELnews web page to include more timely monthly lake level data. Read more about it below.

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^a Water levels are referenced to International Great Lakes (Vertical) Datum 1985 (IGLD85).  For more information, please visit International Great Lakes Datum Update – Great Lakes Coordinating Committee

^a Lake level changes are based on the differences in levels at the beginning of the month and not the monthly average levels.

^a At the beginning of February, all of the Great Lakes were at least 29 cm above their chart datum level. Chart datum is a reference elevation for each lake that provides more information on the depth of water for safe boat navigation on the lakes. For more information, please visit Low Water Datum – Great Lakes Coordinating Committee.

^b Water levels are referenced to International Great Lakes (Vertical) Datum 1985 (IGLD85).  For more information, please visit International Great Lakes Datum Update – Great Lakes Coordinating Committee

Water levels forecast

Lake Superior is currently above its average level and is expected to remain so under most water supply conditions.as

Lake Michigan-Huron is expected to remain above average under most water supply conditions.

Lake Erie is expected to stay above average under most water supply scenarios.

Lake Ontario is above average and is expected to remain so under typical water supply conditions within the next few months. Water levels could move further above average if wetter than average water supply conditions are experienced or move below average if drier than average conditions prevail.

For more information on the probable range of water levels, consult the LEVELnews note on projections.  

For a graphical representation of recent and forecasted water levels on the Great Lakes, refer to the Canadian Hydrographic Service’s monthly water levels bulletin.

^a As a percentage of long-term average (LTA).
^b Environment and Climate Change Canada – Canadian Precipitation Analysis System
^c <5% extremely wet; <25% very wet; <45% wet; 45-55% average; >55% dry; >75% very dry;    >95% extremely dry.
^dPlease refer to the LEVELnews What is net basin supply for a description of net basin supply.

Note: The figures contained in this report are provisional and are subject to change. Data are calculated from the best available observations at the time of posting.

More timely Great Lakes water level data now available

In order to distribute the raw water level data to the public in a more timely manner, preliminary data from the previous month will now be published on the same website as LEVELnews (LEVELnews: monitoring Great Lakes-St. Lawrence River water levels - Canada.ca). It is expected that this table will be updated within the first week of the next month and LEVELnews will follow later in the month with a more detailed description of the lake level information and forecasts. The table contains the average level for the last month for each lake, how it compares to the long-term average, the record values, and the change since the previous month.

Flood Information

With water levels remaining high on some lakes, there is a high risk of flooding. Great Lakes water levels are difficult to predict weeks in advance due to natural variations in weather. To stay informed about Great Lakes water levels and flooding, visit the Ontario flood forecasting and warning program.

Additional information can also be found on the International Lake Superior Board of Control website, and the International Lake Ontario–St. Lawrence River Board website.

Information on current water levels and marine forecasts

Daily levels: Current daily lake-wide average levels of all the Great Lakes are available at Great Lakes - Daily Water Levels for This Month in Meters (army.mil). The daily average water level is an average taken from a number of gauges across each lake and is a good indicator of the overall lake level when it is changing relatively rapidly due to recent high precipitation.

Hourly levels: Hourly lake levels from individual gauge sites can be found at the Government of Canada Great Lakes Water Level Gauging Stations Map. These levels are useful for determining real-time water levels at a given site, however, it should be noted that they are subject to local, temporary effects on water levels such as wind and waves.

Marine forecasts: Visit the Great Lakes water levels and related data webpage under the “Wave and wind data” heading for marine forecasts and wave heights. Current marine forecasts for Lakes Superior, Huron, Erie and Ontario are available as well as text bulletins of recent wave height forecasts.   

For more information:

Frank Seglenieks (Editor) and Nicole O’Brien
Boundary Water Issues
Meteorological Service Canada
Environment and Climate Change Canada
Burlington, ON L7S 1A1
Email: LEVELnews-infoNIVEAU@ec.gc.ca