LEVELnews: Great Lakes and St. Lawrence River water levels, January 2019

Volume 27, Number 1

Above average water supplies continue

Above-average water supplies to all the Great Lakes in December continued a general trend that has been occurring across the Great Lakes basin since January 2013. The 14 year period prior to 2013 (1999 to 2012) saw all of the Great Lakes at or below average for much of this time. Lake Michigan–Huron set its period-of-record (1918-2018) monthly mean low level in January 2013 and all the Great Lakes were at least 17 cm below their January-monthly-mean level in 2013. However, since January 2013, generally above average water supplies to the Great Lakes basin, due mainly to above average precipitation, have left all of the lakes at least 20 cm above average levels to start 2019.

December monthly levels

All the Great Lakes had above average monthly mean water levels in December. Lake Erie was the highest above average while Lake Ontario was the closest to average for the month.

Great Lakes water level information:
December 2018 monthly mean level
Lake Compared to monthly average (1918-2017) Compared to one year ago
Superior 27 cm above   5 cm below
Michigan-Huron 50 cm above  4 cm above
St. Clair 56 cm above 11 cm above
Erie 60 cm above 15 cm above
Ontario 20 cm above 5 cm below

Lake level changes

Above average water supplies to the lakes for December with the combination of above average outflows and seasonally high evaporation rates resulted in variable level changes over the month.

Beginning-of-January lake levels

All the Great Lakes beginning-of-January levels were at least 24 cm above average and all lakes, except Lake Superior, were at or above levels seen at the beginning of January 2018.

Great Lakes water level information:
beginning-of-January 2019 level
Lake Compared to beginning-of-month average (1918-2017) Compared to one year ago
Superior 29 cm above  5 cm below
Michigan-Huron 52 cm above  8 cm above
St. Clair 61 cm above 12 cm above
Erie 62 cm above 20 cm above
Ontario 24 cm above  2 cm above

Ice conditions on lakes

The ice cover on the Great Lakes was below average to begin January 2019. The Great Lakes basin on average has about 16% ice cover on its lakes for of the week of January 15 but this year had only a little bit more than 10% cover. More information on Great Lakes ice conditions can be found on the Canadian Ice Service Great Lakes web site. With below average ice conditions and colder winter temperatures the potential for above average evaporation in coming months is possible.

Water levels forecast

Relative to their beginning-of-January levels and with average water supply conditions, levels of lakes Superior, Michigan–Huron and Erie fall through the month of January and Lake Ontario rises. Based on past conditions on the lakes (1918–2017), all the Great Lakes are likely to remain above average into the spring. Lakes Superior, Michigan–Huron and Erie are expected to stay above average for the next four months, even if very dry conditions are encountered. The probable range of future levels looking forward to April for Lake Superior are between 16 cm and 34 cm above average, for Lake Michigan–Huron are between 35 cm and 62 cm above average and for Lake Erie are between 27 cm and 77 cm above average. Levels of Lake Ontario could fall below average by March, if dry conditions occur. Lake Ontario is estimated to be between 12 cm below average to 57 cm above average by April. For more information on how the probable range of water levels is forecasted see the July 2018 edition of LEVELnews.  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.


December precipitation over the Great Lakes a,b
Lake %
Great Lakes Basin 83%
Lake Superior 64%
Lake Michigan-Huron 83%
Lake Erie
(including Lake St. Clair)
Lake Ontario 101%
December outflows from the Great Lakes a
Lake %
Lake Superior 112%
Lake Michigan-Huron 116%
Lake Erie 121%
Lake Ontario 124%

a As a percentage of December long-term average.
b United States Army Corps of Engineers

Note : These figures are preliminary.


For more information:

Derrick Beach (Editor)
Boundary Water Issues
Meteorological Service Canada
Environment and Climate Change Canada
Burlington ON L7S 1A1
Tel.: 905-336-4714
Fax: 905-319-6939
Email: ec.LEVELnews-infoNIVEAU.ec@canada.ca

Rob Caldwell
Great Lakes-St. Lawrence Regulation Office
Meteorological Service Canada
Environment and Climate Change Canada
111 Water Street East
Cornwall ON K6H 6S2
Tel.: 613-938-5864

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