LEVELnews
Great Lakes–St. Lawrence River Water Levels
Volume 21, Number 4
10 April 2013
Relatively Dry Conditions Return During March
After a few months of generally wetter-than-average conditions, relatively dry conditions returned to the Great lakes basin in March. As is normal for this time of year, water levels on each of the Great Lakes, except Lake Superior, began or continued their seasonal rise in March, but at a slower-than-average rate due to the relatively dry conditions. Lake Superior, which typically does not begin to rise until April, fell more than average during March. Downstream of the lakes, below-average outflows from Lake Ontario and near-average outflows from the Ottawa River resulted in water levels at Montreal Harbour remaining well below average for this time of year.
- Lake Superior’s level fell by 4 cm during March, 3 cm more than it has on average over
the 1918–2012 period of record. - Lake Michigan–Huron’s level increased 2 cm during March, one-half its average March increase
of 4 cm. - Lake Erie’s level rose by 2 cm during March, 11 cm less than its average March increase
of 13 cm. - Lake Ontario’s rose by 4 cm during February, 11 cm less than its average March increase
of 15 cm. - Montreal Harbour’s monthly mean level in March was 82 cm below average and 111 cm lower
than it was during March of last year.
Relative to their beginning-of-April levels and assuming average water supply conditions, the levels of each of the lakes are expected to rise during April. Montreal Harbour's monthly mean level in April is expected to rise compared to its March level.
| Lake | Compared to Monthly Average (1918–2012) | Compared to One Year Ago |
|---|---|---|
| Superior | 32 cm below | 2 cm below |
| Michigan–Huron | 67 cm below | 37 cm below |
| St. Clair | 26 cm below | 35 cm below |
| Erie | 15 cm below | 44 cm below |
| Ontario | 10 cm below | 39 cm below |
| Lake | Compared to Beginning-of-Month Average (1918–2012) | Compared to One Year Ago |
|---|---|---|
| Superior | 33 cm below | 8 cm below |
| Michigan–Huron | 68 cm below | 39 cm below |
| St. Clair | 34 cm below | 41 cm below |
| Erie | 22 cm below | 44 cm below |
| Ontario | 17 cm below | 37 cm below |
Summer Outlook
We’ve only turned the corner into spring and people are beginning to wonder what water levels will be like this summer on the Great Lakes. It’s a question that is asked a lot at this time of year, but one that can’t be answered with a high degree of certainty so early into the season. We can however, look to the monthly Water Levels bulletin prepared by the Canadian Hydrographic Service for an idea of the range of levels we might see over the next six months. The March 2013 edition of the bulletin contains a six-month water levels forecast from April to September 2013 for each of the Great Lakes, Lake St. Clair and Montreal Harbour.
Right now, it looks like the levels of lakes Superior, Michigan–Huron, St. Clair and Erie will remain below average throughout this spring and summer. Levels on these lakes will most likely be lower than they were last year, and Lake Michigan–Huron could set new record low levels if it experiences low water supply conditions. In Lake Ontario’s case, there is a possibility that its level could climb above average if it receives average or higher water supplies over the next few months. The current forecast also suggests that levels on Lake Ontario will be higher than they were last year.
Although water levels are likely to fall somewhere within the probable ranges provided, what actually happens will depend on the water supply conditions over the next few months. For up-to-date information on water level conditions, visit the Candian Hydrograpgic Service website.
| Lake | % |
|---|---|
| Great Lakes Basin | 61% |
| Lake Superior | 88% |
| Lake Michigan–Huron | 65% |
| Lake Erie (including Lake St. Clair) | 43% |
| Lake Ontario | 32% |
| Lake | % |
|---|---|
| Lake Superior | 82% |
| Lake Michigan–Huron | 91% |
| Lake Erie | 97% |
| Lake Ontario | 95% |
*As a percentage of the long-term March average.
Note: These figures are preliminary.
For more information:
Chuck Southam (Editor)
Boundary Water Issues Unit
MSC - Operations Ontario
Environment Canada
P.O. Box 5050
Burlington ON L7R 4A6
Tel.: 905-336-4955
Fax: 905-336-8901
Email: water.levels@ec.gc.ca
Jacob Bruxer
Great Lakes–St. Lawrence Regulation Office
MSC - Operations Ontario
Environment Canada
111 Water Street East
Cornwall ON K6H 6S2
Tel.: 613-938-5725
- Date Modified: