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New water level resources: |
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- Daily
water levels [PDF]
This chart from the U.S. Army Corp shows daily water levels (difference
from datum) in comparison to last year and long term averages,
and shows the predicted water levels for the next six months.
- Weekly
Great Lakes water level update [PDF]
This is text newsletter from the U.S. Army Corp providess a weekly
update on the Great Lakes conditions including weather, water
levels, and alerts.
- Current
water level data plot [site]
NOAA/NOS-CO-OPS records Lake St. Clair water level data every
6 minutes at the NOAA St. Clair shores weather station. Plot of
data is here, but loads slowly.
- Historical
water level data plot [site]
Enter dates to plot your own graph of past water levels at the
St. Clair shores weather station.
- Lake
St. Clair Daily levels [GIF]
NOAA graph comparing monthly Min, Max, and Mean levels of Lake
St. Clair
- Annual
Average water levels on Lake St. Clair [GIF]
NOAA graph comparing average annual lake levels to mean level
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News
Letter Information  
Great Lakes News Letter
U.S. Army Corps of Engineers,
Detroit District Monthly newsletter summarizes data for the
first and sixth months of the 6-month forecast, in comparison to historical
levels.
|
| Physical
Features of the Great Lakes: |
| The Great Lakes
system is a chain of lakes and connecting channels descending like
a series of steps toward the Atlantic Ocean. Lake Superior, located
at the top of the chain, is about 183 meters (601.7 feet) above sea
level, while Lake Ontario stands at about 74.7 meters (245.1 feet).
(Select the adjacent image, courtesy of the U.S. Army Corps of Engineers,
Detroit District, for a larger view of the Great Lakes-St. Lawrence
system's profile.) Water from Lake
Superior flows into Lake Huron through the St. Mary's River. Since
Lake Michigan and Lake Huron are connected by the broad and deep
Straits of Mackinac and stand at virtually the same elevation, they
are often referred to as one lake hydrologic ally; that is, Lakes
Michigan-Huron. From Lakes Michigan-Huron, water flows through the
St. Clair River, Lake St. Clair and the Detroit River into Lake
Erie. Lake Erie discharges through the Niagara River and the Welland
Canal into Lake Ontario. The portion of flow diverted to Lake Ontario
through the Welland Canal is relatively small (about 4 to 5 percent
of the total Lake Erie outflow). Water from Lake Ontario flows to
the Atlantic Ocean through the St. Lawrence River. The average St.
Lawrence River flow, recorded at Cornwall, Ontario, during the period
1900-95, is 6,910 cubic meters (244,000 cubic feet) per second.
This average outflow is relatively small (less than 1 percent per
year) in comparison to the total volume of water contained in the
system. |
Profile
of the Great Lakes and the - St. Lawrence System: |
|
| Only the outflows
from lakes Superior and Ontario are regulated via control structures,
and may be varied within limits in accordance with their respective
regulation plans. The outflows from lakes Michigan-Huron and Erie
are controlled exclusively by the hydraulic characteristics of their
outlet rivers. The immense
storage capacities of the Great Lakes, in combination with their
restricted outflow capacities, allows the lakes to absorb large
variations in water supplies, while maintaining remarkably steady
outflows compared with other large rivers. For example, the highest
St. Lawrence River flow is only 2.3 times greater than its lowest
rate. In contrast, the Mississippi River at St. Louis, Missouri,
has a maximum flow about 30 times its minimum.
Because of the size of the Great Lakes
and the limited discharge capacities of their outlet rivers, extremely
high or low levels can persist for a considerable time, even when
water supplies change significantly. |
Great
Lakes Physical Data: |
| |
Lake
Superior |
Lake
Michigan |
Lake
Huron |
Lake
St. Clair |
Lake
Erie |
Lake
Ontario |
Total |
Water
Surface Area (a)
(square miles) |
31,700 |
22,300 |
23,000 |
400 |
9,900 |
7,600(c) |
94,900 |
Land
Drainage Area (b)
(square miles) |
49,300 |
45,600 |
51,700 |
6,100 |
23,600 |
27,500(c) |
203,800 |
Maximum
Depth
(Feet below Chart Datum) |
1,330 |
923 |
750 |
21(d) |
210 |
802 |
|
Volume
(e)
(cubic meters) |
2,900 |
1,180 |
850 |
- |
116 |
393 |
|
(a) Water surface
areas do not include area of connecting channels.
(b) Land areas include the total drainage are to the outlet
of the upstream lake.
(c) Areas include area down the St. Lawrence Power Project at
Cornwall Ontario.
(d) Deepest sounding outside of dredged navigation channel,
which has a project depth of 27 feet.
(e) Water surface at Chart Datum. |
|
Water
Levels of the Great Lakes: |
| The levels of each
of the Great Lakes depends on the balance between the quantity of
water entering the lake and the quantity of the water leaving the
lake. If these quantities remain exactly the same, the general lake
level is constant. If more water enters the lake than leaves it, the
volume of water in the lake increases, causing the lake level to rise
and, with no artificial outlet control outflow to increase. If less
water enters lake than leaves it, the opposite is true. |
| Hydrologic
Data: |
| Great
Lakes |
| Monthly
Water Level Elevations |
Lake
Superior |
Lake
Michigan-Huron |
Lake
St. Clair |
Lake
Erie |
Lake
Ontario |
| Average |
600.61 |
578.33 |
573.40 |
570.50 |
244.73 |
| Maximum |
602.24 |
581.62 |
576.69 |
573.70 |
248.60 |
| Year
of occurrence |
1985 |
1986 |
1986 |
1986 |
1952 |
| Minimum |
598.23 |
575.35 |
569.86 |
567.49 |
241.45 |
| Year
of occurrence |
1926 |
1964 |
1936 |
1936 |
1934 |
| Range,
Winter Low to Summer High, Monthly Means* |
| Average |
1.2 |
1.2 |
1.7 |
1.6 |
2.0 |
| Maximum |
2.1 |
2.1 |
3.3 |
2.8 |
3.6 |
| Minimum |
0.4 |
0.4 |
0.4 |
0.9 |
0.7 |
|
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