In a Nutshell, Lake levels at mid-October 2018:
- were 11 in. / 30 cm. above the long-term October average
- had risen about 6 in. / 15 cm. since August
- were about the same as a year ago; and
- were 4 in. / 10 cm. short of the October record high set in 1985.
Precipitation and Lake Levels Inextricably Linked
Precipitation and Great Lakes water levels are inextricably linked, despite man’s feeble efforts to control, or “manage,” this vast, high-volume, inland system. Indeed, organizations like the International Lake Superior Board of Control, which manages Lake Superior outflows at Salt Ste. Marie, have a disclaimer stating:
The Board stresses that hydrologic conditions are the primary driver of water level fluctuations. Water levels of the Great Lakes cannot be fully controlled through regulation of outflows, nor can regulation completely eliminate the risk of extreme water levels from occurring during periods of severe weather and water supply conditions.
Water Levels Rose 2 in. / 5 cm. from August to September
The U. S. Army Corps of Engineers is also involved in Great Lakes water management, directly supporting the U.S. Secretariat of the International Joint Commission. According to recent updates from the Corps, precipitation within the Great Lakes basin was 11% below average in September. By contrast, the Corps separates out Lake Superior’s watershed, noting it received 3,52 in. / 8.94 cm of September rain, making it the only lake to receive average levels of precipitation.
Water levels on all but one of the Great Lakes declined from August to September and that one lake was Superior, where water levels rose by 2 in. / 5.08 cm. Still, in contrast to September, 2017, water levels eased over the past year, declining by 4 in. / 10 cm. to September, 2018.
Water Levels Rose 4 in. / 10 cm from September to October
Moving one month forward this autumn, the Corps notes that, as of October 19th, Lake Superior had risen 4 in. / 10 cm. over a one month period from mid-September. The Corps attributes this rise to the significant rainfall occurring over the Superior watershed during the same period. This puts mid-October lake levels at about the same level as October, 2017, but up 11 in. / 30 cm. on the long-term average October water level. The highest October on record was in 1985, but Superior is still 4 in. / 10 cm. short of that level. In contrast, Lake Superior is 28 in. / 71.12 cm above its lowest October average, which was recorded in 1925.
The Corps also provides forward-looking forecasts and says that, in the coming month, Superior outflows through the St. Mary’s River will be above average and water levels on Superior will decline by 2 in. (5 cm).
Call a Guage
While one might think that the water level is the same across the entire lake, except in the case where a seiche comes into play, a call to a couple of the numbers listed below will show that this is not the case. Each number provides brief, real-time data on lake levels for that station, including fluctuation over the past 24 hours and comparison to “chart datum,” essentially a 1985 baseline.
- at Thunder Bay – (807) 344-3141
- at Rossport – (807) 824-2250
- at Michipicoten – (705) 856-0077
- at Gros Cap – (705) 779-2052
- above the lock at Sault Ste Marie – (705) 949-2066
- below the lock at Sault Ste Marie – (705) 254-7989
- Nov. 23, 2017 Infosuperior article: “Interactive Tour – Lake Superior Outflows“
- infosuperior.com/data – real-time Lake Superior data including the Great Lakes Water Level Viewer, Great Lakes Water Levels Dashboard, Real Time Water Levels for Rivers Flowing to Superior
- U.S. Army Corps of Engineers Update on Lake Superior Hydrology for September
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