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LEVELnews
Great Lakes–St. Lawrence River Water Levels
Volume 19, Number 9
13 September 2011
Water Levels Decline on Each Lake During August
Water levels on each of the Great Lakes fell during August. Although outflows from Lake Superior were below average in August, because the water supply that Lake Superior received during the month was even more below average, its level declined by 2 cm this August. In comparison, its average August rise is 1 cm. Similar conditions caused the level of Lakes Michigan–Huron to decline by 7 cm this past month, which is almost twice its average August decline of 4 cm. Lake Erie received below-average water supplies during August. This, combined with an above-average outflow, caused Lake Erie’s level to fall by 12 cm this August, which is 4 cm more than its average decline of 8 cm for the month. Lake Ontario received above-average water supplies during August. However, this was more than offset by its above-average August outflow. As a result, Lake Ontario’s level declined by 17 cm last month, which is a bit more than its average August decline of 15 cm.
| August 2011 Monthly Mean Level | Beginning-of-September 2011 Level | |||
|---|---|---|---|---|
| Lake | Compared to Monthly Average (1918–2010) | Compared to One Year Ago | Compared to Beginning-of-Month Average (1918–2010) | Compared to One Year Ago |
| Superior | 25 cm below | 8 cm above | 28 cm below | 5 cm above |
| Michigan-Huron | 32 cm below | Same | 34 cm below | 1 cm below |
| St. Clair | 1 cm above | 11 cm above | 2 cm above | 13 cm above |
| Erie | 13 cm above | 19 cm above | 12 cm above | 20 cm above |
| Ontario | 6 cm above | 4 cm above | 5 cm above | 4 cm above |
Six-Month Forecast
With average water supply conditions, the level of Lake Superior is expected to remain about the same during September. The levels of each of the remaining Great Lakes and Lake St. Clair are expected to fall as they continue their annual seasonal declines.
For a graphical representation of recent and forecasted water levels on each of the Great Lakes and on Lake St. Clair, compared to their 1918–2010 period-of-record monthly average and extreme levels, please refer to the August 2011 edition of the Canadian Hydrographic Service’s monthly water levels bulletin.
Great Lakes Water Levels and Related Data
To know what Great Lakes water levels are like right now, to track them as they change from day to day, to see what they might be like over the next six months, or to see what they have been like in the past, please visit Environment Canada’s Great Lakes Water Levels and Related Data Web page. There is a selection of links to “current and recent water level data,” “water level forecasts,” and “historical water levels.” This page also provides related data on precipitation, water temperature and ice cover.
| August Precipitation over the Great Lakes* | |||
| Great Lakes Basin | 99% | Lake Erie | 129% |
| Lake Superior | 89% | (including Lake St. Clair) | |
| Lakes Michigan-Huron | 84% | Lake Ontario | 144% |
| August Outflows from the Great Lakes* | |||
| Lake Superior | 75% | Lake Erie | 104% |
| Lake Huron | 92% | Lake Ontario | 110% |
*As a percentage of the long-term August average.
NOTE: These figures are preliminary.
International Upper Great Lakes Study
More than 1000 people attended a dozen public meetings that were held this summer in the United States and Canada, where Study Board members and researchers provided a status report on Phase 2 regulation and restoration options for the lakes. Download the presentation from the public meetings, and the progress report on Phase 2, from the Study Board’s website.
- Date Modified: