Lake Superior 11 Inches Above October Average
Posted on: October 30, 2018
U. S. Army Corps of Engineers Lake Superior water levels graph
Above: U. S. Army Corps of Engineers Lake Superior water levels graph through October, 2018. Click the graph to view a larger, higher definition version.

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.

The compensating works on the St. Marys River.
Outflows from Lake Superior can be increased or decreased through the Compensating Works, a gated dam at the head of the St. Marys River. (Photo: Terry Wurdeman)

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

The Text-A-Buoy system was featured in an August 31st Infosuperior article. The article outlines how readers can text any of several Lake Superior buoys to receive a reply providing real-time weather conditions like wind speed, water and air temperature. The Canadian Hydrographic Service operates a similar system for its water level gauges at stations throughout the Great Lakes. In this case, texting is not possible, rather real-time lake level data is provided through a standard phone call—phone numbers for Canadian gauges are provided below.


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.

Phone Numbers for Lake Superior Water Level Gauges
(operated by the Canadian Hydrographic Service)
  • at Thunder Bay – (807) 344-3141
  • at Rossport – (807) 824-2250
  • at Michipicoten – (705) 856-0077
  • at Gros Cap – (705) 779-2052
Phone Numbers for St. Marys River Water Level Gauges
(operated by the Canadian Hydrographic Service)
  • above the lock at Sault Ste Marie – (705) 949-2066
  • below the lock at Sault Ste Marie – (705) 254-7989


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