LEVELnews: Great Lakes–St. Lawrence River water levels, volume 24 number 7

Great Lakes-St. Lawrence River Water LevelsVolume 24, Number 7

July 2016

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Superior Wet, Rest of Lakes Dry

Lake Superior saw a very wet June, while all the other lakes saw dry conditions continue, resulting in Superior water levels rising much more than average while Michigan-Huron’s rise was below average and Erie and Ontario’s levels declined.

  • The monthly mean water level of Lake Superior was 17 cm above its period-of-record (1918-2015) average in June and 2 cm lower than June 2015.
  • Lake Michigan-Huron’s mean level in June was 30 cm above average and 16 cm higher than last year’s June level.
  • Lake Erie’s mean monthly level was 28 cm above average and 8 cm higher than June 2015.
  • Lake Ontario was 3 cm below its June average and the same level as last year.
  • The dry conditions from the Great Lakes once again extended into the St. Lawrence River basin where the levels near Montreal fell even further below average in June.

The wet conditions in Lake Superior caused the lake to rise 13 cm over the month of June, considerably more than its average (1918-2015) rise of 8 cm. Lake Michigan-Huron only rose 1 cm in June, compared to its average rise of 6 cm. Lake Erie’s level fell 7 cm in June when on average it rises 2 cm. Lake Ontario fell 5 cm in June, when on average it declines only 1 cm.


Great Lakes Water Level Information:
June 2016 Monthly Mean Level
Lake Compared to
Monthly Average
(1918-2015)

Compared to
One Year Ago
Superior
17 cm above
2 cm below
Michigan-Huron
30 cm above
16 cm above
St. Clair
34 cm above
7 cm above
Erie
28 cm above
8 cm above
Ontario
3 cm below
Same

 

Great Lakes Water Level Information:
Beginning-of-July 2016 Level
Lake Compared to
Beginning-of-Month
Average
(1918-2015)
Compared to
One Year Ago
Superior
18 cm above
1 cm below
Michigan-Huron
28 cm above
12 cm above
St. Clair
34 cm above
9 cm below
Erie
24 cm above
14 cm below
Ontario
5 cm below
21 cm below


Beginning-of-July Lake Levels

Lake Superior’s beginning-of-July level was 18 cm above average (1918-2015) and 1 cm below last year’s. Lake Michigan-Huron’s beginning-of-July level was 28 cm above average, 12 cm higher than last year and the highest it has been since 1998. Lake Erie was 24 cm above average at the beginning of July but 14 cm lower than the same time last year. Lake Ontario’s level at the start of July was 5 cm below average and 21 cm below this time last year.

Chart Datum on the Great Lakes

At times you may hear the Great Lakes levels referenced to chart datum. A chart datum is a horizontal plane used to refer current lake levels to in order to provide more information on the depth of water for safe boat navigation on the lakes. The chart datum used on navigation charts for the Great Lakes is a low-water level set from recorded lake levels for each lake so that lake levels are expected to be above the chart datum 95% of the time. At the beginning of July all of the Great Lakes levels were at least 46 cm above chart datum level. Nautical charts reference the bottom of the lake to the chart datum, so for instance, if a location on the nautical chart indicates that the bottom of the lake is 1 m below chart datum, then using July 1 water levels, you can tell that the depth of water will be at least 1.46 m at that location. For more information on chart datum you can refer to the Fisheries and Oceans Canada web page on vertical datums and the chart datum for each of the Great Lakes is given in Canadian Hydrographic Service’s monthly water levels bulletin.

Summer Level Outlook

Relative to their beginning-of-month levels, and assuming average water supply conditions, Lake Superior is expected to continue its seasonal rise during July, Michigan-Huron is expected to stay at about the same level as it reaches its seasonal peak for the year, and Lakes Erie and Ontario are expected to decline through July. 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.

 

June Precipitation over the Great Lakes Footnote1
Lake
%
Great Lakes Basin
83%
Lake Superior
129%
Lake Michigan-Huron
65%
Lake Erie
(including Lake St. Clair)
70%
Lake Ontario
60%

 

June Outflows from the Great Lakes Footnote1
Lake
%
Lake Superior
119%
Lake Michigan-Huron
109%
Lake Erie
109%
Lake Ontario
103%

 

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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