LEVELnews
Great Lakes–St. Lawrence River Water Levels
Volume 20, Number 6
20 June 2012
Water Level Changes Reflect Water Supply Conditions
The March water supplies to lakes Superior and Michigan–Huron were above average, due in large part to above-average runoff from snowmelt. Conversely, a lack of snow cover for the basins of lakes Erie and Ontario limited the amount of runoff those lakes received from snowmelt, leading to below-average supplies for the month for the lakes. The water level changes experienced on each lake during March reflect their respective water supply conditions.
- Lake Superior: The level of Lake Superior increased by 6 cm during March. On average, Lake Superior's level falls by 1 cm during March, as this lake does not usually begin its seasonal rise until April. The lake's larger-than-average increase this March is welcome, given the lake's continuing below-average water level condition. However, the early start to the lake's seasonal rise may mean smaller-than-average increases during April and May.
- Lakes Michigan–Huron: The level of Lakes Michigan–Huron increased by 10 cm during March, which is twice the 1918–2011 period-of-record average increase of 5 cm for the month. As with Lake Superior, Lakes Michigan-Huron's larger-than-average start to its seasonal rise is welcome, but may also result in smaller-than-average increases during the upcoming months.
- Lake Erie: Lake Erie ended March at the same level as the beginning of the month. On average, Lake Erie starts its seasonal rise early in March and increases by 14 cm during the month. This year, the lake's level actually fell by a couple of centimetres during the first two weeks of March before climbing back to its beginning-of-March level by the end of the month. Lake Erie's lack of any increase in March may be welcomed by some, given the lake's above-average water level condition at present.
- Lake Ontario: The level of Lake Ontario fell by 1 cm during March. On average, the level of Lake Ontario increases by 15 cm during March as it continues its annual seasonal rise. Similar to Lake Erie, the level of Lake Ontario fell a couple of centimetres during the first half of the month before starting to rise, and the lake's small decrease in March may be also appreciated by persons concerned about its above-average water level condition at present.
| Lake | Compared to Monthly Average (1918–2011) | Compared to One Year Ago |
|---|---|---|
| Superior | 30 cm below | 6 cm above |
| Michigan-Huron | 30 cm below | 19 cm above |
| St. Clair | 9 cm above | 32 cm above |
| Erie | 29 cm above | 33 cm above |
| Ontario | 29 cm above | 36 cm above |
| Lake | Compared to Beginning-of-Month Average (1918–2011) | Compared to One Year Ago |
|---|---|---|
| Superior | 25 cm below | 12 cm above |
| Michigan-Huron | 28 cm below | 20 cm above |
| St. Clair | 7 cm above | 25 cm above |
| Erie | 22 cm above | 26 cm above |
| Ontario | 20 cm above | 23 cm above |
Six-Month Forecast
For a graphical representation of recent and forecasted water levels on each of the Great Lakes and on Lake St. Clair, compared to their 1918–2011 period-of-record monthly averages and extreme levels, please refer to the March 2012 edition of the Canadian Hydrographic Service's monthly water levels bulletin.
Public Information Sessions
The International Joint Commission (IJC) will hold 12 public information sessions during May and June to discuss a draft new approach to managing water levels and flows in the Lake Ontario and St. Lawrence River (LOSLR) system.
The flow of water from Lake Ontario down the St. Lawrence River is regulated at the Moses-Saunders Dam in accordance with the IJC's 1956 order of approval. The new approach would allow for more variability in Lake Ontario water levels to help restore environmental conditions, while moderating extreme high and low water levels to benefit other basin interests. Details about the new approach, the times and locations of the public information sessions, and how to provide comments are available on the IJC's LOSLR website.
| Great Lakes Basin | 101% |
|---|---|
| Lake Superior | 111% |
| Lakes Michigan-Huron | 106% |
| Lake Erie (including Lake St. Clair) | 104% |
| Lake Ontario | 63% |
| Lake Superior | 81% |
|---|---|
| Lakes Michigan-Huron | 96% |
| Lake Erie | 115% |
| Lake Ontario | 120% |
*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
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
- Date Modified: