LEVELnews
Great Lakes - St. Lawrence River Water Levels
Volume 19, Number 10
13 October 2011
Water Supply Conditions Vary by Basin Location
In September, water supplies to the basins of lakes Superior and Michigan–Huron were below average for the second consecutive month, while local supplies to the Lake Ontario and Lake Erie basins were above average.
Although outflows from Lake Superior were below average in September, the below-average supplies it received caused the water level of Lake Superior to decline by 3 cm this September, compared to its average September decline of 1 cm. Similarly, the level of Lakes Michigan–Huron declined by 9 cm this past month, which is 3 cm more than its average 6 cm September decline.
The above-average water supply received by Lake Erie during September helped stall its seasonal decline. Lake Erie’s level declined by only 2 cm during September, which is much less than its average decline of 9 cm for the month. For Lake Ontario the above-average supplies it received during September were more than offset by its above-average outflows during the month. As a result, Lake Ontario’s level fell by 16 cm last month, compared to its average September decline of 13 cm.
| |||||||||||||||||||||||||||||||||||||||||
As indicated by the beginning-of-October differences provided in the water level information table, the levels of lakes Superior and Michigan–Huron remain below their respective averages for the 1918–2010 period of record. In comparison, the levels of lakes St. Clair, Erie and Ontario are above their averages. The level of Lake Superior began October just 1 cm lower than it was at the same time last year, while the level of Lakes Michigan–Huron was 4 cm lower than it was one year ago. The levels of the other lakes began October higher than they were a year ago. Since 1918, there have been only five years with a lower beginning-of-October level on Lake Superior. Lakes Michigan–Huron’s beginning-of-October level has been lower than this year’s 20 times since 1918. In contrast, the Lake Erie level at the beginning of October has only been higher 26 times since 1918.
Six-Month Forecast
With average water supply conditions, the levels of each of the Great Lakes and Lake St. Clair are expected to fall during October 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 the extreme levels, please refer to the September 2011 edition of the Canadian Hydrographic Service’s monthly water levels bulletin.
Storm Season Reminder
Autumn often brings storms that pack high winds to the Great Lakes region. Watching large waves crash against the shore can be an awe-inspiring sight, but it is important to stand well back from the water’s edge during a storm. Otherwise, there is a risk of being swept into the lake by a storm-generated wave.
| September Precipitation over the Great Lakes* | |||
| Great Lakes Basin | 112% | Lake Erie | 188% |
| Lake Superior | 88% | (including Lake St. Clair) | |
| Lakes Michigan-Huron | 107% | Lake Ontario | 107% |
| September Outflows from the Great Lakes* | |||
| Lake Superior | 71% | Lake Erie | 101% |
| Lake Huron | 90% | Lake Ontario | 107% |
*As a percentage of the long-term September 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
David Fay
Great Lakes–St. Lawrence
Regulation Office
MSC – Operations Ontario
Environment Canada
111 Water Street East
Cornwall ON K6H 6S2
Tel.: 613-938-5725
For information regarding reproduction rights, please contact Public Works and Government Services Canada at 613-996-6886 or at droitdauteur.copyright@tpsgc-pwgsc.ca.
- Date Modified: