LEVELnews: Great Lakes and St. Lawrence River water levels, January 2018

Volume 26, Number 1

Wet 2017 leaves all lakes higher to start 2018

All the Great Lakes continued to show above average water levels at the beginning of February. Water levels are predicted to stay above average at least into the spring for all the lakes. Levels on the St. Lawrence River were mixed with below average levels on the upper river and record high levels reached on the lower river due to ice impacts and high outflows from Lake Ontario at the end of January.

December monthly lake levels

All of the lakes had monthly mean levels above average in December.

  • The December monthly mean water level of Lake Superior was 32 cm above its period-of-record (1918–2016) average and 18 cm higher than December 2016. Lake Superior’s monthly December level was the second highest December mean level on record and 9 cm below the record high set in 1985.
  • Lake Michigan–Huron’s mean level in December was 46 cm above average, 28 cm higher than last December’s level and the highest since 1986.
  • Lake Erie’s mean monthly level was 41 cm above average, 23 cm above its level the previous December and was last seen this high in 2011.
  • Lake Ontario’s mean monthly December level was 25 cm above average, 31 cm higher than the level last year but was higher at this time of year as recent as 2006.

Lake level changes

All lake levels declined over the month of December in part due to a number of factors that varied between each lake that included increased evaporation that is common for all lakes at this time of year, the beginning of snow and ice formation, high outflows and drier conditions seen in some of the lakes.

  • Lake Superior received well above average water supplies in December which more than offset the above average outflow resulting in its level declining by only 2 cm when its average (1918–2016) decline is 8 cm.
  • Lake Michigan–Huron dropped by 9 cm over December due to dry conditions when on average it declines 5 cm.
  • Lake Erie fell 9 cm over December when on average it rises 2 cm mainly due to a combination of average supply conditions with high outflow.
  • Lake Ontario received above average water supplies but these were offset by above-average outflows resulting in its levels falling 8 cm over December when on average it rises 1 cm over the month.
Great Lakes water level information:
December 2017 monthly mean level
Lake Compared to monthly average (1918-2016) Compared to one year ago
Superior 32 cm above 18 cm above
Michigan-Huron 46 cm above 28 cm above
St. Clair 45 cm above 24 cm above
Erie 41 cm above 23 cm above
Ontario 25 cm above 31 cm above
Great Lakes water level information:
beginning-of-January 2018 level
Lake Compared to beginning-of-month average (1918-2016) Compared to one year ago
Superior 34 cm above 20 cm above
Michigan-Huron 43 cm above 25 cm above
St. Clair 49 cm above 27 cm above
Erie 38 cm above 20 cm above
Ontario 22 cm above 27 cm above

Beginning-of-January lake levels

All the Great Lakes began 2018 with levels that were well above average.

  • Lake Superior’s beginning-of-January level was 34 cm above average (1918–2016), 20 cm above the level at this time last year and 6 cm below the record high for this time of year set in 1986.
  • Lake Michigan–Huron’s beginning-of-January level was 43 cm above average, 25 cm higher than last year and the highest it has been since 1998.
  • Lake Erie was 38 cm above average at the beginning of January, 20 cm above this time last year but has been this high as recently as 2012.
  • Lake Ontario’s level at the start of January was 22 cm above average, 27 cm above this time last year and has been this high as recently as 2007.
  • At the beginning of January, all of the lakes were at least 50 cm above their chart datum level.

Water levels forecast

Relative to their beginning-of-January levels and assuming average water supply conditions all the Great Lake levels are expected to decline through January. 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
Lake %
Great Lakes Basin 71%
Lake Superior 107%
Lake Michigan-Huron 62%
Lake Erie
(including Lake St. Clair)
Lake Ontario 62%
December outflows from the Great Lakes a
Lake %
Lake Superior 123%
Lake Michigan-Huron 115%
Lake Erie 119%
Lake Ontario 122%

a  As a percentage of the long-term December average.
    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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