LEVELnews
Great Lakes–St. Lawrence River Water Levels
Volume 21, Number 7
9 July 2013
June 2013 Sees Large Rises in Lakes Erie and Ontario Levels
Wet conditions were experienced throughout the Great Lakes basin during June, especially on lakes Erie and Ontario which experienced record and near-record rises, respectively, in their water levels for the month of June. Downstream of the Great Lakes, Montreal Harbour levels remained near average.
- Following a very wet May, above-average water supplies and below-average outflows resulted in Lake Superior’s level rising by 10 cm during June, 2 cm more than its 1918–2012 period-of-record average rise of 8 cm during the month.
- Relatively wet conditions continued as well for Lake Michigan–Huron, causing it to rise by 7 cm, 2 cm more than its average June rise of 5 cm.
- Conditions proved extremely wet over the Lake Erie basin during June, resulting in a record June rise of 20 cm during the month, 19 cm more than its average June rise of 1 cm. The lake’s previous record June rise was 16 cm back in 1996.
- On Lake Ontario, below-average outflows combined with very high supplies resulted in the lake rising by 22 cm during a month where the lake falls by 1 cm on average, and tying June 2010 for the second highest June rise on record. The lake’s record June rise of 26 cm occurred in 1947.
- The monthly mean level at Montreal Harbour was 3 cm above average during June and 100 cm higher than June’s level last year.
The levels of all the Great Lakes are now above last year’s levels at this time of year, but all lakes remain below their respective 1918–2012 average levels for the beginning of July, with the exception of Lake Ontario. Lake Superior’s level was 4 cm above last year’s level at the beginning of July, and was the highest it has been at the beginning of July since 2009. Including the past three years, lower beginning-of-July levels have only been recorded 12 times since 1918 on Lake Superior. Lake Michigan–Huron’s beginning-of-July level is 48 cm below average, but 2 cm above last year’s level at the same time. Lower beginning-of-July levels have been recorded on Lake Michigan–Huron 14 times since 1918, including last year. Levels at the beginning of July on both lakes Erie and Ontario continue to remain closer to the middle of their respective ranges, being 1 cm below and 12 cm above average, respectively. Since 1918, July has begun with lower levels 43 times on Lake Erie. Last year’s beginning-of-July level on Lake Erie was 14 cm lower than this year’s. Lake Ontario is now 30 cm above last year’s level at this time. However, levels have been higher at the beginning of July 28 times on Lake Ontario since 1918, most recently in 2011.
| Lake | Compared to Monthly Average (1918–2012) | Compared to One Year Ago |
|---|---|---|
| Superior | 18 cm below | 6 cm above |
| Michigan–Huron | 49 cm below | 2 cm below |
| St. Clair | 18 cm below | 1 cm above |
| Erie | 10 cm below | 1 cm above |
| Ontario | 6 cm above | 20 cm above |
| Lake | Compared to Beginning-of-Month Average (1918–2012) | Compared to One Year Ago |
|---|---|---|
| Superior | 16 cm below | 4 cm above |
| Michigan–Huron | 48 cm below | 2 cm above |
| St. Clair | 6 cm below | 13 cm above |
| Erie | 1 cm below | 14 cm above |
| Ontario | 12 cm above | 30 cm above |
Water Level Forecast
Relative to their beginning-of-July levels and assuming average water supply conditions, lakes Superior and Michigan–Huron are expected to rise in July, while lakes St. Clair, Erie, and Ontario are expected to begin their annual seasonal declines. Assuming average water supplies, forecasts indicate that Montreal Harbour's monthly mean level in July is expected to fall, as is typical for this time of year, but remain well above chart datum.
For a graphical representation of recent and forecasted water levels on each of the Great Lakes, Lake St. Clair and Montreal Harbour compared to their respective period-of-record monthly averages and extreme levels please refer to the June 2013 edition of the Canadian Hydrographic Service’s monthly water levels bulletin.
| Lake | % |
|---|---|
| Great Lakes Basin | 110% |
| Lake Superior | 89% |
| Lake Michigan–Huron | 102% |
| Lake Erie (including Lake St. Clair) | 144% |
| Lake Ontario | 153% |
| Lake | % |
|---|---|
| Lake Superior | 94% |
| Lake Michigan–Huron | 89% |
| Lake Erie | 92% |
| Lake Ontario | 88% |
*As a percentage of the long-term June 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
Rob Caldwell
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: