The latest figures from US Army Corp of Engineers show recent rainfall slightly increasing water levels but forecasts are still well below long-term average.
Newest figures show water levels tracking low water forecast.
Despite well above average precipitation levels in June, the latest figures on Great Lakes water levels show a continued below average forecast for the single body of water that makes up Lakes Michigan, Huron and Georgian Bay.
The latest forecast report just posted by the U.S. Army Corp of Engineers says current water levels on Michigan-Huron in May were 14 inches below the long-term average levels and 7 inches below last year. All other Great Lakes were also below their long-term averages, but none by as much as Michigan-Huron.
This has been the case now for over the past decade. The recent International Joint Commission study on the St. Clair river attributes 5 inches of this water level decline to unapproved changes occurring in the St. Clair river with the bulk of the remaining losses attributed to climate change impacts with more expected to come.
More worrisome is that the Army Corp is projecting levels on Michigan-Huron could be below chart datum by the end of the year. Chart datum, also known as low water datum, is the reference point used on navigational charts to measure the depth of water throughout the lakes.
At the end of June, Michigan-Huron was about eight inches above chart datum. The Army Corp is predicting a very slight rise in July, followed by the usual late-season decline with levels dropping to chart datum later in the year.
Anyone who has looked at the water level graphs over the years notices a familiar pattern on how the levels change within a year – they start off low in the winter, go up steadily in the spring and then start dropping off gradually from July until the end of the year. What’s unusual about this year’s graph for Michigan-Huron (and therefore, Georgian Bay) is that the normal springtime increase was completely missing and the normal yearly upswing was delayed until well into June.
You can see the latest US Army Corp of Engineers graphs here:
USACE - Monthly Bulletin of Lake Levels for the Great Lakes
USACE - Daily Great lakes Water Levels
